Debt - Deferred Financing Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Financing costs	$ 25,315	$ 24,446
Less: accumulated amortization	(10,027)	(7,039)
Total deferred financing costs, net	15,288	17,407
Amortization of financing costs	4,100	4,700	$ 5,000
Revolving Credit Facility | Unsecured revolving credit facility
Debt Instrument [Line Items]
Net deferred financing costs	$ 6,300	$ 8,300