SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cash Equivalents and Recent Accounting Pronouncements (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and Cash Equivalents
Cash equivalents	$ 0	$ 0
Recently Announced Accounting Pronouncements
Cash and cash equivalents at beginning of period	136,988,000	113,354,000	$ 170,563,000
Cash and cash equivalents at end of period	118,756,000	136,988,000	113,354,000
Cash, cash equivalents, restricted cash, and restricted cash equivalents at beginning of period	214,484,000	194,927,000	225,641,000
Net increase (decrease) in cash, cash equivalents, restricted cash, and restricted cash equivalents	(1,017,000)	19,557,000	(30,714,000)
Total of cash, cash equivalents, restricted cash, and restricted cash equivalents at end of period	$ 213,467,000	214,484,000	194,927,000
Mortgage Loans
Concentrations of Credit Risk
Period of originated loans within which they are transferred or sold	60 days
As previously reported
Recently Announced Accounting Pronouncements
Cash and cash equivalents at beginning of period	$ 136,988,000	113,354,000	170,563,000
Net increase (decrease) in cash and cash equivalents		23,634,000	(57,209,000)
Cash and cash equivalents at end of period		136,988,000	113,354,000
Cash provided by (used in) operating activities: change in restricted cash and pledged securities		$ 4,268,000	$ (26,495,000)