Condensed Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 1,231	$ (20,000)
Other comprehensive income:
Unrealized gain on derivative contracts	35,268	4,566
Changes in foreign currency translation	4,565	4,875
Other comprehensive income	39,833	9,441
Comprehensive income (loss)	41,064	(10,559)
Comprehensive income attributable to noncontrolling interest	940
Comprehensive income (loss) attributable to common shareholders	$ 40,124	$ (10,559)