Summary of Significant Accounting Policies (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), tax effect	$ (1,099)	$ 121	$ (1,978)
Accumulated other comprehensive loss	(741,814)	(807,877)	(841,553)	$ (659,687)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(12,913)	(16,073)	(15,723)	$ (21,074)
Net unrealized gains on investment securities available for sale, net of income taxes of $78, $7, and $21, respectively
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), tax effect	(78)	(7)	(21)
Accumulated other comprehensive loss	212	7	46
Pension-related amounts, net of income taxes of $4,771, $5,799, and $5,692, respectively
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), tax effect	(4,771)	(5,799)	(5,692)
Accumulated other comprehensive loss	$ (13,125)	$ (16,080)	$ (15,769)