Noncontrolling Interests Property Partnerships (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Activity of Noncontrolling Interests [Roll Forward]
Beginning Balance			$ 1,683,760
Capital contributions			(37,148)	$ (147,772)
Net income	$ 14,850	$ 14,340	46,484	33,967
Accumulated other comprehensive income (loss)	(433)	(300)	(1,031)	2,220
Ending Balance	1,711,028		1,711,028
Property Partnerships Member
Activity of Noncontrolling Interests [Roll Forward]
Beginning Balance			1,683,760	1,530,647
Capital contributions			37,148	147,772
Net income			46,484	33,967
Accumulated other comprehensive income (loss)			432	(2,272)
Distributions			(56,796)	(41,439)
Ending Balance	$ 1,711,028	$ 1,668,675	$ 1,711,028	$ 1,668,675