Fair Value Measurements - Fair Value of Company's Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets [Abstract]
Note receivable	$ 0	$ 16,618
Liabilities:
Credit facility	(603,585)	(643,742)
Notes payable	(619,675)	(224,330)
Carrying amount | Recurring basis
Assets [Abstract]
Real estate loans receivable	47,923	39,154
Note receivable	0	16,618
Liabilities:
Credit facility	(610,000)	(651,000)
Notes payable	(625,000)	(225,000)
Mortgage debt	(174,424)	(123,632)
Carrying amount | Interest Rate Swap | Recurring basis
Assets [Abstract]
Derivative assets	13,679	13,881
Carrying amount | Embedded derivatives | Recurring basis
Liabilities:
Derivative liabilities	0	(5,571)
Fair value | Recurring basis
Assets [Abstract]
Real estate loans receivable	47,464	39,154
Note receivable	0	16,618
Liabilities:
Credit facility	(610,000)	(651,000)
Notes payable	(626,223)	(214,584)
Mortgage debt	(176,493)	(125,420)
Fair value | Interest Rate Swap | Recurring basis
Assets [Abstract]
Derivative assets	13,679	13,881
Fair value | Embedded derivatives | Recurring basis
Liabilities:
Derivative liabilities	$ 0	$ (5,571)