Acquisition Activity (Details Textual) $ in Thousands |
1 Months Ended | 3 Months Ended | 12 Months Ended | ||||
|---|---|---|---|---|---|---|---|
|
Jan. 23, 2019
USD ($)
|
Jul. 25, 2018
USD ($)
shares
|
Mar. 31, 2019
USD ($)
|
Mar. 31, 2018
USD ($)
|
Dec. 31, 2018
USD ($)
|
Dec. 17, 2018
USD ($)
|
May 31, 2004
USD ($)
|
|
| Business Acquisition [Line Items] | |||||||
| Payments to Acquire Businesses, Net of Cash Acquired | $ 15,378 | $ 0 | $ 8,689 | ||||
| Number Of Banking Centers | 19 | ||||||
| Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt | $ 4,124 | ||||||
| First Personal Bank [Member] | |||||||
| Business Acquisition [Line Items] | |||||||
| Business Acquisition Description Of Consideration Paid | Merger, each First Personal stockholder holding 100 or more shares of First Personal common stock received fixed consideration of (i) 0.1246 shares of Bancorp common stock, and (ii) $6.67 per share in cash for each outstanding share of First Personal common stock. Stockholders holding less than 100 shares of First Personal common stock received $12.12 in cash and no stock consideration for each outstanding share of First Personal common stock. Any fractional shares of Bancorp common stock that a First Personal stockholder would have otherwise received in the First Personal Merger were cashed out in the amount of such fraction multiplied by $42.95. | ||||||
| Business Combination, Consideration Transferred | $ 15,600 | ||||||
| Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares | 161,875 | ||||||
| Payments to Acquire Businesses, Net of Cash Acquired | $ 8,700 | ||||||
| Business Acquisition, Transaction Costs | $ 1,800 | ||||||
| AJS Bancorp Inc [Member] | |||||||
| Business Acquisition [Line Items] | |||||||
| Business Acquisition Description Of Consideration Paid | each AJSB stockholder holding 100 or more shares of AJSB common stock received fixed consideration of (i) 0.2030 shares of NWIN common stock, and (ii) $7.20 per share in cash for each outstanding share of AJSB’s common stock. Stockholders holding less than 100 shares of AJSB common stock received $16.00 in cash and no stock consideration for each outstanding share of AJSB common stock. Any fractional shares of NWIN common stock that an AJSB stockholder would have otherwise received in the AJSB Merger were cashed out in the amount of such fraction multiplied by $43.01. | ||||||
| First Personal Statutory Trust I [Member] | |||||||
| Business Acquisition [Line Items] | |||||||
| Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt | $ 4,124 | ||||||
| Equity Securities Description of Variable Rate Basis | LIBOR plus 275 basis points | ||||||
| Business Acquisition Date of Expiration Agreement | Jun. 17, 2034 | ||||||
| Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Debt Redeemed | $ 4,124 | ||||||
| AJSB [Member] | |||||||
| Business Acquisition [Line Items] | |||||||
| Business Combination, Consideration Transferred | $ 32,900 | ||||||
| Payments to Acquire Businesses, Net of Cash Acquired | $ 15,400 | ||||||
| Business Acquisition, Transaction Costs | $ 2,100 | ||||||
| Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Fair Value Method | 416,478 | ||||||