Adoption of ASC Topic 842, Leases, Effective January 1, 2019 - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net lease assets	$ 869,989		$ 873,600
Accrued and other liabilities	104,443		97,724
Operating Lease liability	18,093	$ 20,000
Prepaid expenses	$ 11,477		$ 10,294
Lease, Practical Expedients, Package [true false]	true
Lease, Practical Expedient, Land Easement [true false]	false
Lease, Practical Expedient, Use of Hindsight [true false]	false
Lease, Practical Expedient, Lessor Single Lease Component [true false]	true
Lease, Practical Expedient, Short-term Lease Recognition Exemption [true false]	true
ASC Topic 842 Leases [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accrued and other liabilities		115,150
Prepaid expenses		10,258
ASC Topic 842 Leases [Member] | As Adjusted [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net lease assets		17,400
Accrued and other liabilities		17,426
Operating lease asset		20,000
Operating Lease liability		20,000
Prepaid expenses		(36)
Unamortized lease inducements and other accruals		(2,500)
ASC Topic 842 Leases [Member] | As Adjusted [Member] | Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses		$ 100