Income Taxes - Effective income tax reconciliation (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate, Tax Rate Reconciliation
Statutory rate	35.00%	35.00%	35.00%
Effect of:
State and local income taxes, net of federal tax benefit	3.50%	3.40%	4.80%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent	(2.00%)	15.70%	(2.10%)
Reserve for uncertain tax positions	2.50%	(63.80%)	13.90%
Goodwill impairment	(7.60%)	0.00%	0.00%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	1.60%	8.50%	2.50%
Effective income tax rate	33.00%	(1.20%)	54.10%