Accumulated Other Comprehensive Income (Loss) (Schedule of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,117,490	$ 876,853	$ 1,230,575	$ 893,421
Other comprehensive loss before reclassifications	(84,431)	3,332	(224,450)	(15,334)
Amounts reclassified from accumulated other comprehensive income	34	128	68	259
Net current-period other comprehensive (loss) income	(84,397)	3,460
Ending balance	1,062,343	904,510	1,062,343	904,510
Unrealized Loss on Securities Available for Sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(164,717)	(2,917)	(24,698)	15,749
Other comprehensive loss before reclassifications	(84,431)	3,332	(224,450)	(15,334)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Net current-period other comprehensive (loss) income	(84,431)	3,332	(224,450)	(15,334)
Ending balance	(249,148)	415	(249,148)	415
Postretirement Plans Asset (Liability)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(238)	(1,268)	(272)	(1,399)
Other comprehensive loss before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income	34	128	68	259
Net current-period other comprehensive (loss) income	34	128	68	259
Ending balance	(204)	(1,140)	(204)	(1,140)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(164,955)	(4,185)	(24,970)	14,350
Net current-period other comprehensive (loss) income			(224,382)	(15,075)
Ending balance	$ (249,352)	$ (725)	$ (249,352)	$ (725)