Discontinued Operations - Schedule of the Components of Discontinued Operations (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenues	$ 58,258	$ 50,386	$ 42,466	$ 33,656	$ 26,837	$ 18,853	$ 6,017	$ 1,456	$ 6,517	$ 6,944	$ 6,763	$ 14,716
General and administrative expenses													27,799	11,505	10,369
Loss from discontinued operations															(2,138)
Loss on sale of discontinued operations															(271)
Loss from discontinued operations per share common stock:
Basic															$ (1.03)
Diluted															$ (1.03)
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Servicing fees															9,686
Management fees from affiliates															6,312
Total revenues															15,998
General and administrative expenses															12,938
Income from discontinued operations before income taxes															3,060
Income tax provision															(5,198)
Loss from discontinued operations															(2,138)
Loss on sale of discontinued operations															$ (271)
Loss from discontinued operations per share common stock:
Basic															$ (1.03)
Diluted															$ (1.03)