Income Taxes Reconciliation of statutory federal income tax rate to effective income tax rate (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income taxes at federal statutory rate	21.00%	35.00%	35.00%
Effect of state and local income taxes, net of federal tax	4.00%	3.10%	3.30%
Tax accounting method change	(2.50%)	0.00%	0.00%
Changes in tax laws, including the Tax Act	1.00%	18.30%	0.50%
Deferred tax asset valuation allowance	0.90%	(1.10%)	(2.20%)
Tax contingencies	0.10%	(1.00%)	(1.30%)
Other	(0.30%)	(1.90%)	0.20%
Effective rate	24.20%	52.40%	35.50%