Income Taxes (Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal									$ 84,447	$ 58,334	$ 96,364
State and local									18,595	13,409	11,061
Total current									103,042	71,743	107,425
Deferred:
Federal									811	8,508	39,568
State and local									116	964	(48,642)
Total deferred									927	9,472	(9,074)
Total:
Total federal									85,258	66,842	135,932
Total state and local									18,711	14,373	(37,581)
Income tax expense	$ 25,966	$ 25,411	$ 26,451	$ 26,141	$ 26,697	$ 13,700	$ 20,743	$ 20,075	$ 103,969	$ 81,215	$ 98,351