Loans Receivable - Loan Receivables Acquired By Property (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Net book value	$ 239,207	$ 49,929
Percentage	100.00%	100.00%
Office [Member]
Net book value	$ 91,898	$ 40,367
Percentage	38.00%	81.00%
Multifamily [Member]
Net book value	$ 80,750	$ 9,562
Percentage	34.00%	19.00%
Retail [Member]
Net book value	$ 29,757
Percentage	13.00%
Hospitality [Member]
Net book value	$ 24,302
Percentage	10.00%
Industrial [Member]
Net book value	$ 12,500
Percentage	5.00%

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_LoansReceivableNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant