Income Taxes - Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of the Federal statutory income tax rate to the effective income tax rate, Amount
Federal statutory income tax expense	$ 75,217	$ 128,924	$ 130,140
State and local taxes, net of federal income tax benefit	20,817	16,106	13,884
Impact of Tax Reform		47,598
Nontaxable income	(2,037)	(4,974)	(4,628)
Other	(213)	(2,981)	2,255
Total provision for income taxes	$ 93,784	$ 184,673	$ 141,651
Reconciliation of the Federal statutory income tax rate to the effective income tax rate, Percent
Federal statutory income tax rate, Percent	21.00%	35.00%	35.00%
State and local taxes, net of federal income tax benefit (as a percent)	5.81%	4.37%	3.73%
Impact of Tax Reform (as a percent)		12.92%
Nontaxable income (as a percent)	(0.57%)	(1.35%)	(1.24%)
Other (as a percent)	(0.06%)	(0.81%)	0.61%
Effective Income Tax Rate Reconciliation, Percent, Total	26.18%	50.13%	38.10%