Loans Receivable, Part IV (Details) - USD ($) | 6 Months Ended | 9 Months Ended | |
Jun. 30, 2019 | Jun. 30, 2018 | Sep. 30, 2019 | Dec. 31, 2018 |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | $ 1,385,333,000 | $ 1,379,148,000 |
Loans requiring an officers' loans committee review and approval, minimum | | | 500,000 | |
Minimum amount of potential loan exposure to be reviewed by credit management personnel | | | $ 1,000,000 | |
Maximum period of time loan is reviewed if renewed | | | 1 year | |
Period of time sales of real estate owned fair value is based | | | 2 years | |
Impaired Loans Receivable, Recorded Investment [Abstract] | | | | |
Total Impaired, with Reserve, Recorded Investment | | | $ 270,000 | 3,062,000 |
Total Impaired, with no Reserve, Recorded Investment | | | 9,063,000 | 9,038,000 |
Total Impaired, Recorded Investment | | | 9,333,000 | 12,100,000 |
Impaired Loans Receivable, Unpaid Principal Balance [Abstract] | | | | |
Total Impaired with Reserve, Unpaid Principal Balance | | | 679,000 | 3,471,000 |
Total Impaired with no Reserve, Unpaid Principal Balance | | | 10,914,000 | 10,811,000 |
Total Impaired, Unpaid Principal Balance, Total | | | 11,593,000 | 14,282,000 |
Impaired Loans Receivable, Reserve [Abstract] | | | | |
Total Impaired with Reserve, Reserve | | | 52,000 | 186,000 |
Total Impaired with no Reserve, Reserve | | | 0 | 0 |
Impaired Loans, Reserve | | | 52,000 | 186,000 |
Impaired Loans Receivable, Cumulative Charge Offs [Abstract] | | | | |
Total Impaired with Reserve, Cumulative Charge-offs | | | 409,000 | 409,000 |
Total Impaired with no Reserve, Cumulative Charge-offs | | | 1,851,000 | 1,773,000 |
Total Impaired, Cumulative Charge-offs | | | 2,260,000 | 2,182,000 |
Impaired Loans Receivable, Average Recorded Investment [Abstract] | | | | |
Total Impaired with Reserve, Average Recorded Investment | $ 276,000 | $ 575,000 | | |
Total Impaired with no Reserve, Average Recorded Investment | 9,283,000 | 9,060,000 | | |
Total Impaired, Average Recorded Investment, Total | 9,559,000 | 9,635,000 | | |
Impaired Loans Receivable, Interest Paid YTD [Abstract] | | | | |
Total Impaired with Reserve, Interest Paid YTD | 11,000 | 28,000 | | |
Total Impaired with no Reserve, Interest Paid YTD | 443,000 | 377,000 | | |
Total Impaired, Interest Paid YTD | 454,000 | 405,000 | | |
Charge-offs recorded to reduce the unpaid principal balance | | | 1,900,000 | |
Total impaired loans including troubled debt restructurings | | | 4,078,000 | 6,732,000 |
Substandard [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 10,385,000 | 10,921,000 |
Watch [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 9,639,000 | 10,870,000 |
Pass [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 1,365,309,000 | 1,357,357,000 |
Residential Real Estate [Member] | One-to-Four Family [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 489,148,000 | 489,979,000 |
Impaired Loans Receivable, Recorded Investment [Abstract] | | | | |
Total Impaired, with Reserve, Recorded Investment | | | 262,000 | 462,000 |
Total Impaired, with no Reserve, Recorded Investment | | | 7,620,000 | 7,180,000 |
Total Impaired, Recorded Investment | | | 7,882,000 | 7,642,000 |
Impaired Loans Receivable, Unpaid Principal Balance [Abstract] | | | | |
Total Impaired with Reserve, Unpaid Principal Balance | | | 262,000 | 462,000 |
Total Impaired with no Reserve, Unpaid Principal Balance | | | 8,645,000 | 8,120,000 |
Total Impaired, Unpaid Principal Balance, Total | | | 8,907,000 | 8,582,000 |
Impaired Loans Receivable, Reserve [Abstract] | | | | |
Total Impaired with Reserve, Reserve | | | 44,000 | 73,000 |
Total Impaired with no Reserve, Reserve | | | 0 | 0 |
Impaired Loans, Reserve | | | 44,000 | 73,000 |
Impaired Loans Receivable, Cumulative Charge Offs [Abstract] | | | | |
Total Impaired with Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired with no Reserve, Cumulative Charge-offs | | | 1,025,000 | 940,000 |
Total Impaired, Cumulative Charge-offs | | | 1,025,000 | 940,000 |
Impaired Loans Receivable, Average Recorded Investment [Abstract] | | | | |
Total Impaired with Reserve, Average Recorded Investment | 265,000 | 468,000 | | |
Total Impaired with no Reserve, Average Recorded Investment | 7,779,000 | 7,577,000 | | |
Total Impaired, Average Recorded Investment, Total | 8,044,000 | 8,045,000 | | |
Impaired Loans Receivable, Interest Paid YTD [Abstract] | | | | |
Total Impaired with Reserve, Interest Paid YTD | 11,000 | 24,000 | | |
Total Impaired with no Reserve, Interest Paid YTD | 358,000 | 311,000 | | |
Total Impaired, Interest Paid YTD | 369,000 | 335,000 | | |
Total impaired loans including troubled debt restructurings | | | 3,466,000 | 3,584,000 |
Residential Real Estate [Member] | One-to-Four Family [Member] | Substandard [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 7,962,000 | 7,799,000 |
Residential Real Estate [Member] | One-to-Four Family [Member] | Watch [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 6,948,000 | 4,662,000 |
Residential Real Estate [Member] | One-to-Four Family [Member] | Pass [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 474,238,000 | 477,518,000 |
Residential Real Estate [Member] | Multi Family [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 580,657,000 | 597,087,000 |
Impaired Loans Receivable, Recorded Investment [Abstract] | | | | |
Total Impaired, with Reserve, Recorded Investment | | | 0 | 0 |
Total Impaired, with no Reserve, Recorded Investment | | | 687,000 | 1,309,000 |
Total Impaired, Recorded Investment | | | 687,000 | 1,309,000 |
Impaired Loans Receivable, Unpaid Principal Balance [Abstract] | | | | |
Total Impaired with Reserve, Unpaid Principal Balance | | | 0 | 0 |
Total Impaired with no Reserve, Unpaid Principal Balance | | | 1,513,000 | 2,142,000 |
Total Impaired, Unpaid Principal Balance, Total | | | 1,513,000 | 2,142,000 |
Impaired Loans Receivable, Reserve [Abstract] | | | | |
Total Impaired with Reserve, Reserve | | | 0 | 0 |
Total Impaired with no Reserve, Reserve | | | 0 | 0 |
Impaired Loans, Reserve | | | 0 | 0 |
Impaired Loans Receivable, Cumulative Charge Offs [Abstract] | | | | |
Total Impaired with Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired with no Reserve, Cumulative Charge-offs | | | 826,000 | 833,000 |
Total Impaired, Cumulative Charge-offs | | | 826,000 | 833,000 |
Impaired Loans Receivable, Average Recorded Investment [Abstract] | | | | |
Total Impaired with Reserve, Average Recorded Investment | 0 | 0 | | |
Total Impaired with no Reserve, Average Recorded Investment | 715,000 | 874,000 | | |
Total Impaired, Average Recorded Investment, Total | 715,000 | 874,000 | | |
Impaired Loans Receivable, Interest Paid YTD [Abstract] | | | | |
Total Impaired with Reserve, Interest Paid YTD | 0 | 0 | | |
Total Impaired with no Reserve, Interest Paid YTD | 60,000 | 51,000 | | |
Total Impaired, Interest Paid YTD | 60,000 | 51,000 | | |
Total impaired loans including troubled debt restructurings | | | 324,000 | 372,000 |
Residential Real Estate [Member] | Multi Family [Member] | Substandard [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 687,000 | 1,309,000 |
Residential Real Estate [Member] | Multi Family [Member] | Watch [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 484,000 | 491,000 |
Residential Real Estate [Member] | Multi Family [Member] | Pass [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 579,486,000 | 595,287,000 |
Residential Real Estate [Member] | Home Equity [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 18,073,000 | 19,956,000 |
Impaired Loans Receivable, Recorded Investment [Abstract] | | | | |
Total Impaired, with Reserve, Recorded Investment | | | 0 | 107,000 |
Total Impaired, with no Reserve, Recorded Investment | | | 125,000 | 139,000 |
Total Impaired, Recorded Investment | | | 125,000 | 246,000 |
Impaired Loans Receivable, Unpaid Principal Balance [Abstract] | | | | |
Total Impaired with Reserve, Unpaid Principal Balance | | | 0 | 107,000 |
Total Impaired with no Reserve, Unpaid Principal Balance | | | 125,000 | 139,000 |
Total Impaired, Unpaid Principal Balance, Total | | | 125,000 | 246,000 |
Impaired Loans Receivable, Reserve [Abstract] | | | | |
Total Impaired with Reserve, Reserve | | | 0 | 46,000 |
Total Impaired with no Reserve, Reserve | | | 0 | 0 |
Impaired Loans, Reserve | | | 0 | 46,000 |
Impaired Loans Receivable, Cumulative Charge Offs [Abstract] | | | | |
Total Impaired with Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired with no Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired, Cumulative Charge-offs | | | 0 | 0 |
Impaired Loans Receivable, Average Recorded Investment [Abstract] | | | | |
Total Impaired with Reserve, Average Recorded Investment | 0 | 79,000 | | |
Total Impaired with no Reserve, Average Recorded Investment | 129,000 | 145,000 | | |
Total Impaired, Average Recorded Investment, Total | 129,000 | 224,000 | | |
Impaired Loans Receivable, Interest Paid YTD [Abstract] | | | | |
Total Impaired with Reserve, Interest Paid YTD | 0 | 4,000 | | |
Total Impaired with no Reserve, Interest Paid YTD | 6,000 | 4,000 | | |
Total Impaired, Interest Paid YTD | 6,000 | 8,000 | | |
Residential Real Estate [Member] | Home Equity [Member] | Substandard [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 332,000 | 246,000 |
Residential Real Estate [Member] | Home Equity [Member] | Watch [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 0 | 468,000 |
Residential Real Estate [Member] | Home Equity [Member] | Pass [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 17,741,000 | 19,242,000 |
Construction and Land [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 32,952,000 | 13,361,000 |
Impaired Loans Receivable, Recorded Investment [Abstract] | | | | |
Total Impaired, with Reserve, Recorded Investment | | | 0 | 0 |
Total Impaired, with no Reserve, Recorded Investment | | | 0 | 0 |
Total Impaired, Recorded Investment | | | 0 | 0 |
Impaired Loans Receivable, Unpaid Principal Balance [Abstract] | | | | |
Total Impaired with Reserve, Unpaid Principal Balance | | | 0 | 0 |
Total Impaired with no Reserve, Unpaid Principal Balance | | | 0 | 0 |
Total Impaired, Unpaid Principal Balance, Total | | | 0 | 0 |
Impaired Loans Receivable, Reserve [Abstract] | | | | |
Total Impaired with Reserve, Reserve | | | 0 | 0 |
Total Impaired with no Reserve, Reserve | | | 0 | 0 |
Impaired Loans, Reserve | | | 0 | 0 |
Impaired Loans Receivable, Cumulative Charge Offs [Abstract] | | | | |
Total Impaired with Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired with no Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired, Cumulative Charge-offs | | | 0 | 0 |
Impaired Loans Receivable, Average Recorded Investment [Abstract] | | | | |
Total Impaired with Reserve, Average Recorded Investment | 0 | 0 | | |
Total Impaired with no Reserve, Average Recorded Investment | 0 | 0 | | |
Total Impaired, Average Recorded Investment, Total | 0 | 0 | | |
Impaired Loans Receivable, Interest Paid YTD [Abstract] | | | | |
Total Impaired with Reserve, Interest Paid YTD | 0 | 0 | | |
Total Impaired with no Reserve, Interest Paid YTD | 0 | 0 | | |
Total Impaired, Interest Paid YTD | 0 | 0 | | |
Construction and Land [Member] | Substandard [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 0 | 0 |
Construction and Land [Member] | Watch [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 0 | 0 |
Construction and Land [Member] | Pass [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 32,952,000 | 13,361,000 |
Commercial Real Estate [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 233,068,000 | 225,522,000 |
Impaired Loans Receivable, Recorded Investment [Abstract] | | | | |
Total Impaired, with Reserve, Recorded Investment | | | 8,000 | 2,493,000 |
Total Impaired, with no Reserve, Recorded Investment | | | 631,000 | 392,000 |
Total Impaired, Recorded Investment | | | 639,000 | 2,885,000 |
Impaired Loans Receivable, Unpaid Principal Balance [Abstract] | | | | |
Total Impaired with Reserve, Unpaid Principal Balance | | | 417,000 | 2,902,000 |
Total Impaired with no Reserve, Unpaid Principal Balance | | | 631,000 | 392,000 |
Total Impaired, Unpaid Principal Balance, Total | | | 1,048,000 | 3,294,000 |
Impaired Loans Receivable, Reserve [Abstract] | | | | |
Total Impaired with Reserve, Reserve | | | 8,000 | 67,000 |
Total Impaired with no Reserve, Reserve | | | 0 | 0 |
Impaired Loans, Reserve | | | 8,000 | 67,000 |
Impaired Loans Receivable, Cumulative Charge Offs [Abstract] | | | | |
Total Impaired with Reserve, Cumulative Charge-offs | | | 409,000 | 409,000 |
Total Impaired with no Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired, Cumulative Charge-offs | | | 409,000 | 409,000 |
Impaired Loans Receivable, Average Recorded Investment [Abstract] | | | | |
Total Impaired with Reserve, Average Recorded Investment | 11,000 | 28,000 | | |
Total Impaired with no Reserve, Average Recorded Investment | 660,000 | 438,000 | | |
Total Impaired, Average Recorded Investment, Total | 671,000 | 466,000 | | |
Impaired Loans Receivable, Interest Paid YTD [Abstract] | | | | |
Total Impaired with Reserve, Interest Paid YTD | 0 | 0 | | |
Total Impaired with no Reserve, Interest Paid YTD | 19,000 | 11,000 | | |
Total Impaired, Interest Paid YTD | 19,000 | 11,000 | | |
Total impaired loans including troubled debt restructurings | | | 288,000 | 2,776,000 |
Commercial Real Estate [Member] | Substandard [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 639,000 | 678,000 |
Commercial Real Estate [Member] | Watch [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 1,427,000 | 4,343,000 |
Commercial Real Estate [Member] | Pass [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 231,002,000 | 220,501,000 |
Consumer [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 803,000 | 433,000 |
Impaired Loans Receivable, Recorded Investment [Abstract] | | | | |
Total Impaired, with Reserve, Recorded Investment | | | 0 | 0 |
Total Impaired, with no Reserve, Recorded Investment | | | 0 | 0 |
Total Impaired, Recorded Investment | | | 0 | 0 |
Impaired Loans Receivable, Unpaid Principal Balance [Abstract] | | | | |
Total Impaired with Reserve, Unpaid Principal Balance | | | 0 | 0 |
Total Impaired with no Reserve, Unpaid Principal Balance | | | 0 | 0 |
Total Impaired, Unpaid Principal Balance, Total | | | 0 | 0 |
Impaired Loans Receivable, Reserve [Abstract] | | | | |
Total Impaired with Reserve, Reserve | | | 0 | 0 |
Total Impaired with no Reserve, Reserve | | | 0 | 0 |
Impaired Loans, Reserve | | | 0 | 0 |
Impaired Loans Receivable, Cumulative Charge Offs [Abstract] | | | | |
Total Impaired with Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired with no Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired, Cumulative Charge-offs | | | 0 | 0 |
Impaired Loans Receivable, Average Recorded Investment [Abstract] | | | | |
Total Impaired with Reserve, Average Recorded Investment | 0 | 0 | | |
Total Impaired with no Reserve, Average Recorded Investment | 0 | 0 | | |
Total Impaired, Average Recorded Investment, Total | 0 | 0 | | |
Impaired Loans Receivable, Interest Paid YTD [Abstract] | | | | |
Total Impaired with Reserve, Interest Paid YTD | 0 | 0 | | |
Total Impaired with no Reserve, Interest Paid YTD | 0 | 0 | | |
Total Impaired, Interest Paid YTD | 0 | 0 | | |
Consumer [Member] | Substandard [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 0 | 0 |
Consumer [Member] | Watch [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 0 | 0 |
Consumer [Member] | Pass [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 803,000 | 433,000 |
Commercial Loans [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 30,632,000 | 32,810,000 |
Impaired Loans Receivable, Recorded Investment [Abstract] | | | | |
Total Impaired, with Reserve, Recorded Investment | | | 0 | 0 |
Total Impaired, with no Reserve, Recorded Investment | | | 0 | 18,000 |
Total Impaired, Recorded Investment | | | 0 | 18,000 |
Impaired Loans Receivable, Unpaid Principal Balance [Abstract] | | | | |
Total Impaired with Reserve, Unpaid Principal Balance | | | 0 | 0 |
Total Impaired with no Reserve, Unpaid Principal Balance | | | 0 | 18,000 |
Total Impaired, Unpaid Principal Balance, Total | | | 0 | 18,000 |
Impaired Loans Receivable, Reserve [Abstract] | | | | |
Total Impaired with Reserve, Reserve | | | 0 | 0 |
Total Impaired with no Reserve, Reserve | | | 0 | 0 |
Impaired Loans, Reserve | | | 0 | 0 |
Impaired Loans Receivable, Cumulative Charge Offs [Abstract] | | | | |
Total Impaired with Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired with no Reserve, Cumulative Charge-offs | | | 0 | 0 |
Total Impaired, Cumulative Charge-offs | | | 0 | 0 |
Impaired Loans Receivable, Average Recorded Investment [Abstract] | | | | |
Total Impaired with Reserve, Average Recorded Investment | 0 | 0 | | |
Total Impaired with no Reserve, Average Recorded Investment | 0 | 26,000 | | |
Total Impaired, Average Recorded Investment, Total | 0 | 26,000 | | |
Impaired Loans Receivable, Interest Paid YTD [Abstract] | | | | |
Total Impaired with Reserve, Interest Paid YTD | 0 | 0 | | |
Total Impaired with no Reserve, Interest Paid YTD | 0 | 0 | | |
Total Impaired, Interest Paid YTD | $ 0 | $ 0 | | |
Commercial Loans [Member] | Substandard [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 765,000 | 889,000 |
Commercial Loans [Member] | Watch [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | 780,000 | 906,000 |
Commercial Loans [Member] | Pass [Member] | | | | |
Loans and Leases Receivable [Abstract] | | | | |
At December 31, 2016 | | | $ 29,087,000 | $ 31,015,000 |