Commitments and Contingencies - Minimum Aggregate Lease Payments (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Leases [Abstract]
Gross Rents, 2017	$ 26,535
Gross Rents, 2018	26,043
Gross Rents, 2019	26,150
Gross Rents, 2020	25,413
Gross Rents, 2021	24,559
Gross Rents, Thereafter	257,986
Gross Rents, Total lease commitments	386,686
Sublease Rents, 2017	2,259
Sublease Rents, 2018	2,123
Sublease Rents, 2019	2,077
Sublease Rents, 2020	2,009
Sublease Rents, 2021	1,891
Sublease Rents, Thereafter	8,130
Sublease Rents, Total lease commitments	18,489
Net Rents, 2017	24,276
Net Rents, 2018	23,920
Net Rents, 2019	24,073
Net Rents, 2020	23,404
Net Rents, 2021	22,668
Net Rents, Thereafter	249,856
Net Rents, Total lease commitments	$ 368,197