Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Repatriation tax, payment term		8 years
Measurement period adjustments	$ 2,100
Increase in effective tax rate	0.50%
Effective income tax rate	17.60%	30.90%	31.00%
Decrease in effective income tax rate related to share-based compensation	4.70%	7.30%	0.00%
Decrease in effective income tax rate from utilization of foreign credits		1.00%
Impact of tax reform on deferred taxes		8.00%
Income taxes paid	$ 69,700	$ 81,200	$ 74,700
Income tax ruling exemption	9,200	8,900	7,800
Valuation allowance	(6,212)	(6,211)
Net operating loss carryforwards in certain state and international jurisdictions	15,100
Unrecognized tax benefits	24,247	21,417	18,463	$ 7,204
Unrecognized tax benefits that would impact effective tax rate if recognized	18,300	9,100
Interest expense and penalties related to unrecognized tax benefits	1,200	900	$ 300
Interest expense and penalties accrued	$ 2,100	$ 1,000
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in effective income tax rate related to share-based compensation		7.00%