Equity - Schedule of Components of Non-Controlling Interests (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Restricted cash	$ 10,096	$ 14,246
Loans receivable, at fair value	40,665
Accrued interest receivable, prepaid expenses, and other assets	39,974	5,868
Accounts payable, accrued expenses and other liabilities	(56,972)	(21,209)
Non-controlling interests in CT Legacy Partners	38,841	80,009
Non-controlling Interests [Member]
Restricted cash	10,096
Loans receivable, at fair value	40,665
Accrued interest receivable, prepaid expenses, and other assets	16,118
Accounts payable, accrued expenses and other liabilities	(378)
CT Legacy Partners equity	66,501
Equity interests owned by Blackstone Mortgage Trust, Inc.	(27,660)
Non-controlling interests in CT Legacy Partners	$ 38,841