Debt - Deferred Financing Costs, Net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Financing costs	$ 25,237		$ 25,237		$ 24,446
Less: accumulated amortization	(7,985)		(7,985)		(7,039)
Total deferred financing costs, net	17,252		17,252		17,407
Amortization of deferred financing costs	1,000	$ 1,300	2,000	$ 2,600
Unsecured term loan facility | Unsecured Revolving Credit Facility
Debt Instrument [Line Items]
Net deferred financing costs	$ 7,300		$ 7,300		$ 8,300