Parent Company Only Financial Statements - Schedule of Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows From Operating Activities:
Net income (loss)	$ (2,864)	$ (2,865)	$ (3,209)	$ 1,124	$ 563	$ 239	$ 282	$ 96	$ 808	$ (4,387)	$ 1,425	$ 2,518
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Charitable foundation contribution expense										6,093
Deferred income taxes										(40)	126	1,086
Net decrease (increase) in accrued interest receivable										628	39	(81)
Increase in other assets										38	175	3,168
Net increase in other liabilities										3,313	893	(4,101)
Net cash provided by operating activities										8,646	4,343	5,230
Cash Flows From Investing Activities:
Net cash used in investing activities										(135,898)	(43,893)	(6,194)
Cash Flows From Financing Activities:
Proceeds from issuance of common stock										78,191
Funds loaned to the ESOP										(7,238)
Net cash provided by (used in) financing activities										175,260	38,572	(2,191)
Net increase (decrease) in cash and cash equivalents										48,008	(978)	(3,155)
Beginning					$ 11,716				$ 12,694	11,716	12,694	15,849
Ending	59,724	59,724				$ 11,716				59,724	$ 11,716	$ 12,694
Ponce Bank Mutual Holding Company
Cash Flows From Operating Activities:
Net income (loss)										(3,430)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries										(1,523)
Charitable foundation contribution expense										6,093
Deferred income taxes										(1,261)
Increase in other assets										(88)
Net increase in other liabilities										62
Net cash provided by operating activities										(147)
Cash Flows From Investing Activities:
Investment in Ponce Bank										(39,272)
Repayment of ESOP Loan										526
Net cash used in investing activities										(38,746)
Cash Flows From Financing Activities:
Proceeds from issuance of common stock										78,191
Funds loaned to the ESOP										(7,238)
Net cash provided by (used in) financing activities										70,953
Net increase (decrease) in cash and cash equivalents										32,060
Ending	$ 32,060	$ 32,060								$ 32,060