Intangibles - Gross Carrying Amount and Accumulated Amortization of Intangible Assets and Liabilities (Detail) $ in Thousands	Sep. 30, 2017 USD ($)
Intangible assets:
Total intangible assets	$ 129,507
Accumulated amortization:
Total accumulated amortization	(40,997)
Intangible assets, net	88,510
Intangible liabilities:
Below-market lease intangibles	12,693
Accumulated amortization	(1,106)
Intangible liabilities, net	11,587
In-place Lease Intangibles [Member]
Intangible assets:
Total intangible assets	104,735
Accumulated amortization:
Total accumulated amortization	(40,496)
Intangible assets, net	64,239
Below-market Ground Lease Intangibles [Member]
Intangible assets:
Total intangible assets	4,683
Accumulated amortization:
Total accumulated amortization	(62)
Intangible assets, net	4,621
Above-market Lease Intangibles [Member]
Intangible assets:
Total intangible assets	3,299
Accumulated amortization:
Total accumulated amortization	(314)
Intangible assets, net	2,985
Prepaid Ground Lease Rent [Member]
Intangible assets:
Total intangible assets	16,114
Accumulated amortization:
Total accumulated amortization	(94)
Other Intangible Assets
Intangible assets:
Total intangible assets	676
Accumulated amortization:
Total accumulated amortization	$ (31)