Loans Receivable - Allocation of Loans Receivable by Loan Type and Internal Risk Ratings (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 SecurityLoan	Dec. 31, 2012 SecurityLoan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Book value, net	$ 2,047,223	$ 141,500
Subordinate Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans	5	6
Principal Balance	264,898	101,680
Book value, net	246,894	79,000
Subordinate Loans [Member] | Risk Rating 1-3 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans	3	2
Principal Balance	227,350	47,000
Book value, net	219,894	47,000
Subordinate Loans [Member] | Risk Rating 4-5 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans		1
Principal Balance		30,000
Book value, net		30,000
Subordinate Loans [Member] | Risk Rating 6-8 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans	2	3
Principal Balance	37,548	24,680
Book value, net	27,000	2,000
Senior Mortgages Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans	26	1
Principal Balance	1,811,514	62,500
Book value, net	1,800,329	62,500
Senior Mortgages Loans [Member] | Risk Rating 1-3 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans	26
Principal Balance	1,811,514
Book value, net	1,800,329
Senior Mortgages Loans [Member] | Risk Rating 4-5 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans		1
Principal Balance		62,500
Book value, net		$ 62,500