Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Interest and related income	$ 6,944	$ 25,642	$ 28,423	$ 95,187
Less: Interest and related expenses	5,147	21,838	33,902	80,381
Income from loans and other investments, net	1,797	3,804	(5,479)	14,806
Management fees from affiliates	1,546	1,753	4,741	4,927
Servicing fees	2,206	1,460	5,591	2,208
Total other revenues	3,752	3,213	10,332	7,135
General and administrative	7,141	4,941	16,193	19,868
Servicing fee expense
Total other expenses	7,141	4,941	16,193	19,868
Total other-than-temporary impairments of securities		(30,687)		(35,620)
Portion of other-than-temporary impairments of securities recognized in other comprehensive income		173	(160)	(3,098)
Impairment of real estate held-for-sale		(1,055)		(1,055)
Net impairments recognized in earnings		(31,569)	(160)	(39,773)
Valuation allowance on loans held-for-sale				(224)
Recovery of provision for loan losses	2,811	17,152	2,819	34,401
Fair value adjustment on investment in CT Legacy Asset	11,987		19,645
Gain on extinguishment of debt		20,054		271,031
Gain on deconsolidation of subsidiary			146,380
Income from equity investments in unconsolidated subsidiaries	411	307	1,312	2,105
Income before income taxes	13,617	8,020	158,656	269,613
Income tax provision (benefit)	717	(236)	1,783	1,214
Net income	12,900	8,256	156,873	268,399
Net (income) loss attributable to noncontrolling interests	(5,901)	5,466	(81,038)	(1,935)
Net income attributable to Capital Trust, Inc.	6,999	13,722	75,835	266,464
Total assets	581,197	1,539,889	581,197	1,539,889	1,366,316
Balance Sheet Investment
Interest and related income	6,944	25,642	28,423	95,187
Less: Interest and related expenses	5,147	21,838	33,902	80,381
Income from loans and other investments, net	1,797	3,804	(5,479)	14,806
Management fees from affiliates
Servicing fees
Total other revenues
General and administrative	3,381	2,427	6,551	5,372
Servicing fee expense	1,031		1,400	632
Total other expenses	4,412	2,427	7,951	6,004
Total other-than-temporary impairments of securities		(30,687)		(35,620)
Portion of other-than-temporary impairments of securities recognized in other comprehensive income		173	(160)	(3,098)
Impairment of real estate held-for-sale		(1,055)		(1,055)
Net impairments recognized in earnings		(31,569)	(160)	(39,773)
Valuation allowance on loans held-for-sale				(224)
Recovery of provision for loan losses	2,811	17,152	2,819	34,401
Fair value adjustment on investment in CT Legacy Asset	11,987		19,645
Gain on extinguishment of debt		20,054		271,031
Gain on deconsolidation of subsidiary			146,380
Income from equity investments in unconsolidated subsidiaries
Income before income taxes	12,183	7,014	155,254	274,237
Income tax provision (benefit)	167	703	467	2,615
Net income	12,016	6,311	154,787	271,622
Net (income) loss attributable to noncontrolling interests	(5,901)	5,466	(81,038)	(1,935)
Net income attributable to Capital Trust, Inc.	6,115	11,777	73,749	269,687
Total assets	556,003	1,528,441	556,003	1,528,441
Investment Management
Interest and related income
Less: Interest and related expenses
Income from loans and other investments, net
Management fees from affiliates	2,165	2,372	6,597	6,171
Servicing fees	3,237	1,671	6,991	2,840
Total other revenues	5,402	4,043	13,588	9,011
General and administrative	4,379	3,344	11,498	15,740
Servicing fee expense
Total other expenses	4,379	3,344	11,498	15,740
Total other-than-temporary impairments of securities
Portion of other-than-temporary impairments of securities recognized in other comprehensive income
Net impairments recognized in earnings
Fair value adjustment on investment in CT Legacy Asset
Gain on deconsolidation of subsidiary
Income from equity investments in unconsolidated subsidiaries	411	307	1,312	2,105
Income before income taxes	1,434	1,006	3,402	(4,624)
Income tax provision (benefit)	550	(939)	1,316	(1,401)
Net income	884	1,945	2,086	(3,223)
Net (income) loss attributable to noncontrolling interests
Net income attributable to Capital Trust, Inc.	884	1,945	2,086	(3,223)
Total assets	25,194	11,448	25,194	11,448
Inter-Segment Activities
Interest and related income
Less: Interest and related expenses
Income from loans and other investments, net
Management fees from affiliates	(619)	(619)	(1,856)	(1,244)
Servicing fees	(1,031)	(211)	(1,400)	(632)
Total other revenues	(1,650)	(830)	(3,256)	(1,876)
General and administrative	(619)	(830)	(1,856)	(1,244)
Servicing fee expense	(1,031)		(1,400)	(632)
Total other expenses	(1,650)	(830)	(3,256)	(1,876)
Total other-than-temporary impairments of securities
Portion of other-than-temporary impairments of securities recognized in other comprehensive income
Net impairments recognized in earnings
Fair value adjustment on investment in CT Legacy Asset
Gain on deconsolidation of subsidiary
Income from equity investments in unconsolidated subsidiaries
Income before income taxes
Income tax provision (benefit)
Net income
Net (income) loss attributable to noncontrolling interests
Net income attributable to Capital Trust, Inc.
Total assets