Debt and Preferred Equity Investments (Details) (USD $)	9 Months Ended																																																																				3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014 Debt investment		Dec. 31, 2013 Debt investment		Sep. 30, 2014 Total fixed rate		Dec. 31, 2013 Total fixed rate		Sep. 30, 2014 Total fixed rate Jr. Mortgage Participation, March 2015		Dec. 31, 2013 Total fixed rate Jr. Mortgage Participation, March 2015		Sep. 30, 2014 Total fixed rate Jr. Mortgage Participation/Mezzanine Loan, February 2016		Dec. 31, 2013 Total fixed rate Jr. Mortgage Participation/Mezzanine Loan, February 2016		Sep. 30, 2014 Total fixed rate Jr. Mortgage Participation/Mezzanine Loan, May 2016		Dec. 31, 2013 Total fixed rate Jr. Mortgage Participation/Mezzanine Loan, May 2016		Sep. 30, 2014 Total fixed rate Mezzanine Loan, May 2016		Dec. 31, 2013 Total fixed rate Mezzanine Loan, May 2016		Sep. 30, 2014 Total fixed rate Jr. Mortgage Participation, June 2016		Dec. 31, 2013 Total fixed rate Jr. Mortgage Participation, June 2016		Sep. 30, 2014 Total fixed rate Mezzanine Loan, November 2016		Dec. 31, 2013 Total fixed rate Mezzanine Loan, November 2016		Sep. 30, 2014 Total fixed rate Jr. Mortgage Participation/Mezzanine Loan, March 2017		Dec. 31, 2013 Total fixed rate Jr. Mortgage Participation/Mezzanine Loan, March 2017		Sep. 30, 2014 Total fixed rate Other, March 2017		Dec. 31, 2013 Total fixed rate Other, March 2017		Sep. 30, 2014 Total fixed rate Mezzanine Loan, June 2017		Dec. 31, 2013 Total fixed rate Mezzanine Loan, June 2017		Sep. 30, 2014 Total fixed rate Mezzanine Loan, July 2018		Dec. 31, 2013 Total fixed rate Mezzanine Loan, July 2018		Sep. 30, 2014 Total fixed rate Mortgage Loan, February 2019		Dec. 31, 2013 Total fixed rate Mortgage Loan, February 2019		Sep. 30, 2014 Total fixed rate Mortgage Loan, August 2019		Dec. 31, 2013 Total fixed rate Mortgage Loan, August 2019		Sep. 30, 2014 Total fixed rate Mezzanine Loan, September 2021		Dec. 31, 2013 Total fixed rate Mezzanine Loan, September 2021		Sep. 30, 2014 Total fixed rate Mezzanine Loan, November 2023		Dec. 31, 2013 Total fixed rate Mezzanine Loan, November 2023		Mar. 31, 2014 Total fixed rate Jr. Mortgage Participation, June 2014	Sep. 30, 2014 Total fixed rate Jr. Mortgage Participation, June 2014	Sep. 30, 2014 Total fixed rate Junior Mortgage Participation	Sep. 30, 2014 Total floating rate		Dec. 31, 2013 Total floating rate		Sep. 30, 2014 Total floating rate Mezzanine Loan, November 2016		Dec. 31, 2013 Total floating rate Mezzanine Loan, November 2016		Sep. 30, 2014 Total floating rate Mezzanine Loan April 2015		Dec. 31, 2013 Total floating rate Mezzanine Loan April 2015		Sep. 30, 2014 Total floating rate Mortgage/Mezzanine Loan June 2015		Dec. 31, 2013 Total floating rate Mortgage/Mezzanine Loan June 2015		Sep. 30, 2014 Total floating rate Mezzanine Loan, September 2015		Dec. 31, 2013 Total floating rate Mezzanine Loan, September 2015		Sep. 30, 2014 Total floating rate Mezzanine Loan, December 2015		Dec. 31, 2013 Total floating rate Mezzanine Loan, December 2015		Sep. 30, 2014 Total floating rate Mezzanine Loan, March 2016		Dec. 31, 2013 Total floating rate Mezzanine Loan, March 2016		Sep. 30, 2014 Total floating rate Mezzanine Loan, June 2016		Dec. 31, 2013 Total floating rate Mezzanine Loan, June 2016		Sep. 30, 2014 Total floating rate Mezzanine Loan, July 2016		Dec. 31, 2013 Total floating rate Mezzanine Loan, July 2016		Sep. 30, 2014 Total floating rate Mezzanine Loan, December 2016		Dec. 31, 2013 Total floating rate Mezzanine Loan, December 2016		Sep. 30, 2014 Total floating rate Mortgage/Mezzanine Loan, July 2017		Dec. 31, 2013 Total floating rate Mortgage/Mezzanine Loan, July 2017		Sep. 30, 2014 Total floating rate Mortgage/Mezzanine Loan, July 2017		Dec. 31, 2013 Total floating rate Mortgage/Mezzanine Loan, July 2017		Sep. 30, 2014 Total floating rate Mortgage/Mezzanine Loan, September 2017		Dec. 31, 2013 Total floating rate Mortgage/Mezzanine Loan, September 2017		Sep. 30, 2014 Total floating rate Jr. Mortgage Participation/Mezzanine Loan, July 2018		Dec. 31, 2013 Total floating rate Jr. Mortgage Participation/Mezzanine Loan, July 2018		Sep. 30, 2014 Total floating rate Mortgage/Mezzanine Loan, February 2019		Dec. 31, 2013 Total floating rate Mortgage/Mezzanine Loan, February 2019		Sep. 30, 2014 Total floating rate Mezzanine Loan, March 2019		Dec. 31, 2013 Total floating rate Mezzanine Loan, March 2019		Sep. 30, 2014 Total floating rate Mortgage Loan, Repaid May 2014		Dec. 31, 2013 Total floating rate Mortgage Loan, Repaid May 2014		Sep. 30, 2014 Total floating rate Jr. Mortgage Participation, Repaid July 2014		Dec. 31, 2013 Total floating rate Jr. Mortgage Participation, Repaid July 2014		Sep. 30, 2014 Total floating rate Jr. Mortgage Participation/Mezzanine Loan, Repaid July 2014		Dec. 31, 2013 Total floating rate Jr. Mortgage Participation/Mezzanine Loan, Repaid July 2014		Sep. 30, 2014 Total floating rate Mezzanine Loan, Repaid August 2014		Dec. 31, 2013 Total floating rate Mezzanine Loan, Repaid August 2014		Sep. 30, 2014 Total floating rate Jr. Mortgage Participation, Repaid August 2014		Dec. 31, 2013 Total floating rate Jr. Mortgage Participation, Repaid August 2014		Sep. 30, 2014 Total floating rate Mezzanine Loan, Repaid In August 2014		Dec. 31, 2013 Total floating rate Mezzanine Loan, Repaid In August 2014
Debt investment
Increase in debt and preferred equity investments (net of discounts), including investments classified as held-for-sale	$ 476,600,000	$ 497,400,000
Decrease in debt and preferred equity investments (net of discounts), including investments classified as held-for-sale	348,500,000	530,200,000
Aggregate weighted average current yield (as a percent)	10.72%
Funding Obligations					55,037,000				19,555,000				0				0				0				0				0				0				0	[1]			0	[1]			19,555,000	[2]			0				0	[3]			0				0				0	[4]						35,482,000				8,448,000				15,309,000				0				0				8,262,000				0				0	[5]			0				333,000				3,130,000				0				0				0				0				0				0	[6]			0	[7]			0	[7]			0	[8]			0	[8]			0	[8]
Senior Financing					5,246,578,000				3,517,994,000				398,500,000				205,000,000				164,744,000				177,000,000				133,000,000				165,000,000				1,109,000,000	[1]			0	[1]			521,750,000	[2]			539,000,000				0	[3]			0				15,000,000				90,000,000	[4]						1,728,584,000				172,105,000				50,000,000				0				110,000,000				110,295,000				775,000,000				160,000,000	[5]			115,000,000				33,833,000				109,351,000				0				0				55,000,000				0				38,000,000				0	[6]			0	[7]			0	[7]			0	[8]			0	[8]			0	[8]
Carrying Value, Net of Discounts									547,173,000	[9]	385,604,000	[9]	11,913,000	[9]	11,856,000	[9]	70,080,000	[9]	68,319,000	[9]	45,355,000	[9]	44,742,000	[9]	14,298,000	[9]	15,012,000	[9]	49,000,000	[9]	49,000,000	[9]	71,592,000	[9]	71,312,000	[9]	97,101,000	[1],[9]	26,884,000	[1],[9]	65,674,000	[1],[9]	54,099,000	[1],[9]	21,456,000	[2],[9]	20,954,000	[2],[9]	50,412,000	[9]	0	[9]	26,196,000	[3],[9]	0	[3],[9]	667,000	[9]	0	[9]	3,500,000	[9]	3,500,000	[9]	19,929,000	[4],[9]	19,926,000	[4],[9]
Debt and preferred equity investments	1,432,951,000		1,304,839,000		1,077,123,000	[9]	936,475,000	[9]																																																														30,000,000		529,950,000	[9]	550,871,000	[9]	28,855,000	[9]	25,725,000	[9]	29,650,000	[9]	0	[9]	109,252,000	[9]	0	[9]	49,482,000	[9]	49,110,000	[9]	41,675,000	[9]	27,662,000	[9]	73,602,000	[9]	72,823,000	[9]	22,561,000	[5],[9]	22,526,000	[5],[9]	24,909,000	[9]	25,590,000	[9]	11,825,000	[9]	11,798,000	[9]	38,186,000	[9]	0	[9]	22,786,000	[9]	0	[9]	16,835,000	[9]	0	[9]	20,538,000	[9]	20,553,000	[9]	17,996,000	[9]	0	[9]	21,798,000	[9]	0	[9]	0	[6],[9]	30,000,000	[6],[9]	0	[7],[9]	24,046,000	[7],[9]	0	[7],[9]	131,724,000	[7],[9]	0	[8],[9]	59,892,000	[8],[9]	0	[8],[9]	10,873,000	[8],[9]	0	[8],[9]	38,549,000	[8],[9]
Payments to Acquire Investments	421,003,000	393,429,000																																																																				67,300,000
Loan loss reserve	0		(1,000,000)	(7,000,000)	0	[9]	(1,000,000)	[9]
Total, net of reserve					1,077,123,000	[9]	935,475,000	[9]
Accretion of unaccrued interest																																																																					10,100,000
Face amount of mortgages																																																																						66,700,000
Loan participation amount included in other assets and other liabilities																																													41,300,000																				5,000,000																																			7,400,000
Mortgage Loans On Real Estate Commercial And Consumer, Gross																																																					26,400,000																		5,700,000
Mortgage Loans On Real Estate Commercial And Consumer, Discount Amount																																																					$ 200,000																		$ 5,700,000

[1] During the three months ended March 31, 2014, we recognized $10.1 million of previously unaccrued interest income as deemed collectible as a result of the subsequent sale of the property, which closed in June 2014. In connection with the sale of the underlying property, our existing $66.7 million mezzanine loan was defeased and is now shown separately, as it is collateralized by defeasance securities. The buyer assumed our $30.0 million participating interest on the mortgage and we acquired a $67.3 million participating interest on the mezzanine loan.

[2] Carrying value is net of $41.3 million that was participated out, which is included in other assets and other liabilities on the consolidated balance sheets as a result of the transfer not meeting the conditions for sale accounting.

[3] In September 2014, we acquired a $26.4 million mortgage loan at a $0.2 million discount and a $5.7 million junior mortgage participation at a $5.7 million discount. The junior mortgage participation was a nonperforming loan at acquisition and is currently on a non-accrual status.

[4] Carrying value is net of $5.0 million that was participated out, which is included in other assets and other liabilities on the consolidated balance sheets as a result of the transfer not meeting the conditions for sale accounting.

[5] Carrying value is net of $7.4 million that was participated out, which is included in other assets and other liabilities on the consolidated balance sheets as a result of the transfer not meeting the conditions for sale accounting.

[6] This loan was repaid in May 2014.

[7] This loan was repaid in July 2014.

[8] This loan was repaid in August 2014.

[9] Carrying value is net of discounts, original issue discounts and deferred origination fees.