Unaudited Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Unaudited Condensed Consolidated Statement of Comprehensive Income [Abstract]
Net income	$ 79,213	$ 82,048
Other comprehensive income:
Foreign currency translation adjustments	7,401	(9,592)
Total comprehensive income	86,614	72,456
Total comprehensive income attributable to noncontrolling interests	(40)	(57)
Total comprehensive income attributable to common stockholders	$ 86,574	$ 72,399