Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 24,538	$ 23,957	$ 75,058	$ 69,351
Other comprehensive income (loss):
Foreign currency translation adjustments	659	(548)	3,917	(1,013)
Total other comprehensive income (loss)	659	(548)	3,917	(1,013)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	25,197	23,409	78,975	68,338
Net Income (Loss) Attributable to Noncontrolling Interest	354	(110)	1,013	133
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 24,843	$ 23,519	$ 77,962	$ 68,205