Investment in Rental Property and Lease Arrangements - Additional Information (Detail) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2017
USD ($)
Property
|
Dec. 31, 2016
USD ($)
|
Dec. 31, 2015
USD ($)
|
|
| Lessor Lease Description [Line Items] | |||
| Number of real estate properties under operating leases | 513 | ||
| Number of real estate properties under direct financing leases | 15 | ||
| Number of real estate properties under direct financing leases that include land option | 4 | ||
| Lessor, operating lease, existence of option to extend | true | ||
| Lessor, direct financing lease, existence of option to extend | true | ||
| Depreciation expense on investment in rental property | $ | $ 50,360 | $ 37,976 | $ 25,038 |
| Minimum | |||
| Lessor Lease Description [Line Items] | |||
| Lessor operating lease, initial terms | 10 years | ||
| Lessor direct financing leases, initial terms | 10 years | ||
| Maximum | |||
| Lessor Lease Description [Line Items] | |||
| Lessor operating lease, initial terms | 20 years | ||
| Lessor direct financing leases, initial terms | 20 years | ||