CONSOLIDATED CONDENSED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 34,105	$ 12,818	$ 72,495	$ 48,637
Other comprehensive income, before tax:
Change in fair value of derivative instruments	64	187	(2,223)	2,043
Foreign currency translation adjustments	(1,143)	2,693	3,618	(4,285)
Comprehensive income, before tax	33,026	15,698	73,890	46,395
Income tax (expense) benefit related to items of other comprehensive income	(29)	0	62	0
Comprehensive income	$ 32,997	$ 15,698	$ 73,952	$ 46,395