Income Taxes (Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal									$ 73,172	$ 84,447	$ 58,334
State and local									17,417	18,595	13,409
Total current									90,589	103,042	71,743
Deferred:
Federal									(23,799)	811	8,508
State and local									(7,437)	116	964
Total deferred									(31,236)	927	9,472
Total:
Total federal									49,373	85,258	66,842
Total state and local									9,980	18,711	14,373
Income tax expense	$ 15,118	$ 18,289	$ 14,802	$ 11,144	$ 25,966	$ 25,411	$ 26,451	$ 26,141	$ 59,353	$ 103,969	$ 81,215