Fair Values - Schedule of Details of Carrying Amount, Face Amount, and Fair Value of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financial assets
Loans receivable, net	$ 38,400	$ 40,700
Financial liabilities
Repurchase obligations	1,500,000
Carrying Amount [Member]
Financial assets
Cash and cash equivalents	120,456	52,342
Restricted cash	11,392	10,096
Loans receivable, net	3,488,179	2,047,223
Financial liabilities
Repurchase obligations	1,779,650	1,109,353
Convertible notes, net	160,671	159,524
Participations sold	461,078	90,000
Face Amount [Member]
Financial assets
Cash and cash equivalents	120,456	52,342
Restricted cash	11,392	10,096
Loans receivable, net	3,514,032	2,076,411
Financial liabilities
Repurchase obligations	1,779,650	1,109,353
Convertible notes, net	172,500	172,500
Participations sold	461,078	90,000
Fair Value [Member]
Financial assets
Cash and cash equivalents	120,456	52,342
Restricted cash	11,392	10,096
Loans receivable, net	3,514,032	2,058,699
Financial liabilities
Repurchase obligations	1,779,650	1,109,353
Convertible notes, net	186,300	181,772
Participations sold	$ 462,603	$ 90,304