Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Interest and related income	$ 6,763	$ 32,554	$ 21,479	$ 69,545
Less: Interest and related expenses	5,413	32,296	28,754	58,543
Income from loans and other investments, net	1,350	258	(7,275)	11,002
Management fees from affiliates	1,610	1,595	3,195	3,174
Servicing fees	1,365	438	3,385	748
Total other revenues	2,975	2,033	6,580	3,922
General and administrative	4,740	4,649	9,052	14,928
Servicing fee expense
Total other expenses	4,740	4,649	9,052	14,928
Total other-than-temporary impairments of securities				(4,933)
Portion of other-than-temporary impairments of securities recognized in other comprehensive income			(160)	(3,271)
Net impairments recognized in earnings			(160)	(8,204)
Valuation allowance on loans held-for-sale		(224)		(224)
Recovery of provision for loan losses		8,088	8	17,249
Fair value adjustment on investment in CT Legacy Assets	3,704		7,657
Gain on extinguishment of debt		937		250,976
Gain on deconsolidation of subsidiary			146,380
Income from equity investments	205	842	901	1,797
Income before income taxes	3,494	7,285	145,039	261,590
Income tax provision (benefit)	143	1,061	1,066	1,450
Net income	3,351	6,224	143,973	260,140
Less: Net loss attributable to noncontrolling interests	(1,068)	(8,069)	(75,137)	(7,400)
Net income (loss) attributable to Capital Trust, Inc.	2,283	(1,845)	68,836	252,740
Total assets	584,237	2,365,400	584,237	2,365,400	1,366,316
Balance Sheet Investment
Interest and related income	6,763	32,554	21,479	69,545
Less: Interest and related expenses	5,413	32,296	28,754	58,543
Income from loans and other investments, net	1,350	258	(7,275)	11,002
Management fees from affiliates
Servicing fees
Total other revenues
General and administrative	1,642	1,496	3,171	3,428
Servicing fee expense	133	211	369	433
Total other expenses	1,775	1,707	3,540	3,861
Total other-than-temporary impairments of securities				(4,933)
Portion of other-than-temporary impairments of securities recognized in other comprehensive income			(160)	(3,271)
Net impairments recognized in earnings			(160)	(8,204)
Valuation allowance on loans held-for-sale		(224)		(224)
Recovery of provision for loan losses		8,088	8	17,249
Fair value adjustment on investment in CT Legacy Assets	3,704		7,657
Gain on extinguishment of debt		937		250,976
Gain on deconsolidation of subsidiary			146,380
Income from equity investments
Income before income taxes	3,279	7,352	143,070	266,938
Income tax provision (benefit)		2,000	300	2,332
Net income	3,279	5,352	142,770	264,606
Less: Net loss attributable to noncontrolling interests	(1,068)	(8,069)	(75,137)	(7,400)
Net income (loss) attributable to Capital Trust, Inc.	2,211	(2,717)	67,633	257,206
Total assets	563,467	2,360,192	563,467	2,360,192
Investment Management
Interest and related income
Less: Interest and related expenses
Income from loans and other investments, net
Management fees from affiliates	2,229	1,786	4,433	3,800
Servicing fees	1,498	649	3,754	1,181
Total other revenues	3,727	2,435	8,187	4,981
General and administrative	3,717	3,344	7,119	12,126
Servicing fee expense
Total other expenses	3,717	3,344	7,119	12,126
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 Assets
Gain on deconsolidation of subsidiary
Income from equity investments	205	842	901	1,797
Income before income taxes	215	(67)	1,969	(5,348)
Income tax provision (benefit)	143	(939)	766	(882)
Net income	72	872	1,203	(4,466)
Less: Net loss attributable to noncontrolling interests
Net income (loss) attributable to Capital Trust, Inc.	72	872	1,203	(4,466)
Total assets	20,770	9,219	20,770	9,219
Inter-Segment Activities
Interest and related income
Less: Interest and related expenses
Income from loans and other investments, net
Management fees from affiliates	(619)	(191)	(1,238)	(626)
Servicing fees	(133)	(211)	(369)	(433)
Total other revenues	(752)	(402)	(1,607)	(1,059)
General and administrative	(619)	(191)	(1,238)	(626)
Servicing fee expense	(133)	(211)	(369)	(433)
Total other expenses	(752)	(402)	(1,607)	(1,059)
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 Assets
Gain on deconsolidation of subsidiary
Income from equity investments
Income before income taxes
Income tax provision (benefit)
Net income
Less: Net loss attributable to noncontrolling interests
Net income (loss) attributable to Capital Trust, Inc.
Total assets		$ (4,011)		$ (4,011)