Employee Benefit Plans (Fair Value Of Pension Plan Assets By Asset Category) (Details) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021
U.S. government obligations		$ 1,035,406	$ 1,080,720
Government-sponsored enterprise obligations		43,108	51,755
State and municipal obligations		1,767,109	2,096,827
Agency mortgage-backed securities		4,308,427	5,683,000
Non-agency mortgage-backed securities		1,211,607	1,366,477
Asset-backed securities		3,397,801	3,539,219
Pension Plans [Member]
U.S. government obligations		9,960	6,824
Government-sponsored enterprise obligations	[1]	1,022	2,066
State and municipal obligations		6,840	8,000
Agency mortgage-backed securities	[2]	2,871	3,266
Non-agency mortgage-backed securities		2,527	2,974
Asset-backed securities		6,768	7,648
Corporate bonds	[3]	35,234	40,832
Mutual funds	[4]	4,395	6,004
Common stocks	[4]	15,868	27,702
International developed markets	[4]	2,604	3,943
Emerging markets	[4]	307	548
Total		88,396	109,807
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
U.S. government obligations		1,035,406	1,080,720
Government-sponsored enterprise obligations		0	0
State and municipal obligations		0	0
Agency mortgage-backed securities		0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Pension Plans [Member]
U.S. government obligations		9,960	6,824
Government-sponsored enterprise obligations	[1]	0	0
State and municipal obligations		0	0
Agency mortgage-backed securities	[2]	0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Corporate bonds	[3]	0	0
Mutual funds	[4]	4,395	6,004
Common stocks	[4]	15,868	27,702
International developed markets	[4]	2,604	3,943
Emerging markets	[4]	307	548
Total		33,134	45,021
Significant Other Observable Inputs (Level 2) [Member]
U.S. government obligations		0	0
Government-sponsored enterprise obligations		43,108	51,755
State and municipal obligations		1,765,268	2,094,843
Agency mortgage-backed securities		4,308,427	5,683,000
Non-agency mortgage-backed securities		1,211,607	1,366,477
Asset-backed securities		3,397,801	3,539,219
Significant Other Observable Inputs (Level 2) [Member] | Pension Plans [Member]
U.S. government obligations		0	0
Government-sponsored enterprise obligations	[1]	1,022	2,066
State and municipal obligations		6,840	8,000
Agency mortgage-backed securities	[2]	2,871	3,266
Non-agency mortgage-backed securities		2,527	2,974
Asset-backed securities		6,768	7,648
Corporate bonds	[3]	35,234	40,832
Mutual funds	[4]	0	0
Common stocks	[4]	0	0
International developed markets	[4]	0	0
Emerging markets	[4]	0	0
Total		55,262	64,786
Significant Unobservable Inputs (Level 3) [Member]
U.S. government obligations		0	0
Government-sponsored enterprise obligations		0	0
State and municipal obligations		1,841	1,984
Agency mortgage-backed securities		0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Pension Plans [Member]
U.S. government obligations		0	0
Government-sponsored enterprise obligations	[1]	0	0
State and municipal obligations		0	0
Agency mortgage-backed securities	[2]	0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Corporate bonds	[3]	0	0
Mutual funds	[4]	0	0
Common stocks	[4]	0	0
International developed markets	[4]	0	0
Emerging markets	[4]	0	0
Total		$ 0	$ 0

[1] This category represents bonds (excluding mortgage-backed securities) issued by agencies such as the Government National Mortgage Association, the Federal Home Loan Mortgage Corp and the Federal National Mortgage Association.

[2] This category represents mortgage-backed securities issued by the agencies mentioned in (a).

[3] This category represents investment grade bonds issued in the U.S., primarily by domestic issuers, representing diverse industries.

[4] This category represents investments in individual common stocks and equity funds. These holdings are diversified, largely across the financial services, technology services, electronic technology, healthcare technology, and retail trade industries.