v3.7.0.1
Income Taxes Effective Tax Rate Reconciliation (Details)
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]    
U.S. federal statutory tax rate 35.00% 35.00%
State income taxes, net of federal tax benefit 1.40% 2.90%
General business credits (1.00%) (2.60%)
Employee stock-based compensation (1.00%) 0.50%
Other 0.50% 1.00%
Effective tax rate 34.90% 36.80%