Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Effective tax rate (in hundredths)	28.90%	28.10%	27.30%	25.50%
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options			$ 4,623
Minimum [Member]
Significant change in unrecognized tax benefits is reasonably possible, estimated range of change, lower bound	$ 0		0
Maximum [Member]
Significant change in unrecognized tax benefits is reasonably possible, estimated range of change, lower bound	$ 27,899		$ 27,899