Summary of Quarterly Results of Operations (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary Of Quarterly Results Of Operations Details
Revenues	$ 12,183	$ 10,696	$ 9,738	$ 18,321	$ 29,955	$ 28,855	$ 34,586	$ 38,889	$ 44,615	$ 43,147	$ 41,675	$ 44,505
Net income (loss)	122,931	12,900	3,351	140,622	(16,078)	8,256	6,224	253,917	9,915	(134,709)	2,902	(63,452)	279,804	252,319	(185,344)
Net income (loss) attributable to Capital Trust, Inc.	$ 105,189	$ 6,999	$ 2,283	$ 66,553	$ (8,320)	$ 13,722	$ (1,845)	$ 254,585	$ 9,915	$ (134,709)	$ 2,902	$ (63,452)	$ 181,024	$ 258,142	$ (185,344)
Net income (loss) per share of class A common stock:
Basic	$ 4.22	$ 0.30	$ 0.10	$ 2.91	$ (0.37)	$ 0.60	$ (0.08)	$ 11.35	$ 0.44	$ (6.02)	$ 0.13	$ (2.84)	$ 7.72	$ 11.39	$ (8.28)
Diluted	$ 4.06	$ 0.28	$ 0.09	$ 2.74	$ (0.37)	$ 0.57	$ (0.08)	$ 11.04	$ 0.44	$ (6.02)	$ 0.13	$ (2.84)	$ 7.31	$ 10.78	$ (8.28)