Unsecured Revolving Credit Facility - Additional Information (Details) - USD ($)		3 Months Ended
	Jun. 25, 2018	Mar. 31, 2019	Dec. 31, 2018
Line Of Credit Facility [Line Items]
Borrowings under revolving credit facility		$ 52,000,000
Principal balance outstanding under the facility		0	$ 34,000,000
Total deferred finance costs, net		8,400,000	9,000,000
Senior Unsecured Revolving Credit Facility
Line Of Credit Facility [Line Items]
Aggregate total revolving credit commitments	$ 300,000,000
Credit facility term	4 years
Maximum additional availability of the facility	$ 200,000,000
Borrowings under revolving credit facility		52,000,000
Borrowings or repayments under facility		86,000,000
Line of credit facility, unused borrowing capacity		300,000,000
Principal balance outstanding under the facility		0
Interest expense recorded from amortization of deferred financing costs		200,000
Interest expense including unused facility fees		700,000
Senior Unsecured Revolving Credit Facility | Prepaid Expenses and Other Current Assets, Net
Line Of Credit Facility [Line Items]
Total deferred finance costs, net		$ 2,900,000	$ 3,000,000
Senior Unsecured Revolving Credit Facility | Minimum [Member] | LIBOR
Line Of Credit Facility [Line Items]
Annual interest rate	1.45%
Senior Unsecured Revolving Credit Facility | Minimum [Member] | Prime Rate
Line Of Credit Facility [Line Items]
Annual interest rate	0.45%
Senior Unsecured Revolving Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Credit facility extension term	12 months
Senior Unsecured Revolving Credit Facility | Maximum | LIBOR
Line Of Credit Facility [Line Items]
Annual interest rate	2.15%
Senior Unsecured Revolving Credit Facility | Maximum | Prime Rate
Line Of Credit Facility [Line Items]
Annual interest rate	1.15%