Parent Company Only - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net income	$ 5,027	$ 16,156
Adjustments to reconcile net income to net cash provided by operating activities:
Net decrease in prepaid expenses and other assets	(1,537)	289
Net cash used in operating activities	8,257	16,666
Cash flows from investing activities:
Net cash provided by (used in) investing activities	16,874	(95,252)
Cash flows from financing activities:
Repurchases of common stock	(4,065)	(5,973)
Cash dividends paid	(6,412)	(9,071)
Net cash provided by (used in) financing activities	60,975	19,280
Net change in cash and cash equivalents	86,106	(59,306)
Cash and cash equivalents at beginning of the year	40,553	99,859
Cash and cash equivalents at end of the year	126,659	40,553
Territorial Bancorp Inc.
Cash flows from operating activities:
Net income	5,027	16,156
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of Territorial Savings Bank, net of dividends	(5,708)	859
Net decrease in prepaid expenses and other assets	933	1,275
Net decrease in other liabilities	163	(263)
Net cash used in operating activities	415	18,027
Cash flows from financing activities:
Repurchases of common stock	(4,065)	(5,973)
Cash dividends paid	(6,412)	(9,071)
Net cash provided by (used in) financing activities	(10,477)	(15,044)
Net change in cash and cash equivalents	(10,062)	2,983
Cash and cash equivalents at beginning of the year	28,515	25,532
Cash and cash equivalents at end of the year	$ 18,453	$ 28,515