CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 63,302	$ 103,281	$ 169,300	$ 80,098	$ 393,805	$ 615,191	$ 152,968	$ 199,148	$ 415,981	$ 1,361,112	$ 651,490
Other comprehensive income (loss):
Foreign currency translation									(9,436)	20,612	(52,266)
Unrealized gain (loss) on marketable debt securities									14,944	(437)	(310)
Derivative instruments									10,030	2,239	2,607
Total other comprehensive income (loss)									15,538	22,414	(49,969)
Comprehensive income									431,519	1,383,526	601,521
Comprehensive income attributable to noncontrolling interests									6,514	4,642	2,259
Comprehensive income attributable to common stockholders									$ 425,005	$ 1,378,884	$ 599,262