Intangibles - Gross Carrying Amount and Accumulated Amortization of Intangible Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Intangible assets:
Total intangible assets	$ 348,364	$ 159,916
Accumulated amortization:
Total accumulated amortization	(78,423)	(46,072)
Intangible assets, net	269,941	113,844
Intangible liabilities:
Below-market lease intangibles	47,911	14,920
Above-market ground lease intangibles	4,657
Total intangible liabilities	52,568	14,920
Accumulated amortization:
Below-market lease amortization	(8,219)	(1,764)
Above-market ground lease amortization	(2)
Total accumulated amortization	(8,221)	(1,764)
Intangible liabilities, net	44,347	13,156
In-place Lease Intangibles [Member]
Intangible assets:
Total intangible assets	303,410	131,833
Accumulated amortization:
Total accumulated amortization	(74,130)	(45,160)
Intangible assets, net	229,280
Below-market Ground Lease Intangibles [Member]
Intangible assets:
Total intangible assets	4,623	4,623
Accumulated amortization:
Total accumulated amortization	(142)	(85)
Intangible assets, net	4,481
Above-market Lease Intangibles [Member]
Intangible assets:
Total intangible assets	18,541	6,670
Accumulated amortization:
Total accumulated amortization	(3,627)	(600)
Intangible assets, net	14,914
Prepaid Ground Lease Rent [Member]
Intangible assets:
Total intangible assets	16,114	16,114
Accumulated amortization:
Total accumulated amortization	(321)	(151)
Other Intangible Assets
Intangible assets:
Total intangible assets	5,676	676
Accumulated amortization:
Total accumulated amortization	$ (203)	$ (76)