Income Taxes - Tax Reconciliation (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Reconciliation to effective federal income tax rate
Federal statutory rate	34.00%	34.00%
Stock based awards	2.10%	1.20%
State taxes	6.30%	2.10%
Other permanent differences	(0.80%)	0.70%
Impact of uncertain tax positions	(1.20%)	1.70%
Valuation allowance	(1.50%)	0.00%
Other	(0.10%)	(0.10%)
Effective federal income tax rate	38.80%	39.60%