Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Effective tax rate (in hundredths)	24.60%	28.20%	26.40%	26.50%
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options			$ 5,609
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	$ 32,127		$ 32,127