Variable Interest Entities and Noncontrolling Interests - Income or loss attributable to third party investors (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Noncontrolling Interest [Abstract]
Amounts attributable to non-redeemable noncontrolling interests	$ 16,147	$ (46,160)	$ (9,523)	$ (96,118)
Dividends attributable to redeemable noncontrolling interests	(4,586)	(4,588)	(13,756)	(13,761)
Net (income) loss attributable to noncontrolling interests	$ 11,561	$ (50,748)	$ (23,279)	$ (109,879)