Other Investments (Schedule of Other Investments) (Details) (USD $)	12 Months Ended			6 Months Ended		12 Months Ended									3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Apr. 19, 2013 LNR Property LLC (LNR)		Dec. 31, 2013 LNR Property LLC (LNR)	Dec. 31, 2012 LNR Property LLC (LNR)	Sep. 30, 2012 LNR Property LLC (LNR)		Dec. 31, 2011 LNR Property LLC (LNR)	Sep. 30, 2011 LNR Property LLC (LNR)		Sep. 30, 2013 LNR Property LLC (LNR)		Mar. 31, 2012 Madison Funds	Dec. 31, 2013 Madison Funds	Dec. 31, 2012 Madison Funds	Dec. 31, 2011 Madison Funds	Dec. 31, 2013 Oak Hill Funds	Dec. 31, 2012 Oak Hill Funds	Dec. 31, 2011 Oak Hill Funds	Dec. 31, 2013 Real estate equity investments	Dec. 31, 2012 Real estate equity investments	Dec. 31, 2011 Real estate equity investments	Dec. 31, 2013 Other equity method investments		Dec. 31, 2012 Other equity method investments		Dec. 31, 2011 Other equity method investments		Dec. 31, 2011 Oak Hill Advisors
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 197,307,000	$ 387,718,000				$ 0	$ 205,773,000	$ 205,773,000	[1],[2]				$ 0	[1],[2]		$ 67,782,000	$ 56,547,000		$ 21,366,000	$ 29,840,000		$ 62,205,000	$ 47,619,000		$ 45,954,000	[3]	$ 47,939,000	[3]
Other, carrying value	9,902,000	11,125,000
Other investments	207,209,000	398,843,000
Earnings (loss) from equity method investments	41,520,000	103,009,000	95,091,000	45,375,000	[2],[4]	16,465,000	60,669,000	60,669,000	[2],[4]	53,861,000	53,861,000	[2],[4]			13,700,000	14,796,000	10,246,000	3,641,000	4,174,000	5,844,000	1,918,000	2,753,000	21,636,000	(5,273,000)	3,332,000	[3]	4,614,000	[3]	40,944,000	[3]
Included within earnings from equity method investments																															$ 38,400,000

[1] Represents the Company's investment in LNR at December 31, 2013 and 2012, respectively.

[2] The Company recorded its investment in LNR, which was sold in April 2013, on a one quarter lag, therefore, amounts in the Company's financial statements for the year ended December 31, 2013 are based on balances and results from LNR for the period from October 1, 2012 to April 19, 2013. The amounts in the Company's financial statements for the year ended December 31, 2012 and 2011 are based on balances and results from LNR for the years ended September 30, 2012 and 2011, respectively.

[3] For the year ended December 31, 2011, equity in earnings includes $38.4 million of earnings related to Oak Hill Advisors, L.P. and related entities that were sold in October 2011.

[4] LNR reported a net loss for the period from April 1, 2013 to April 19, 2013 which had already been considered in the Company's other than temporary impairment assessment. As such, no equity in earnings was recorded during the quarter ended September 30, 2013. The total equity in earnings recognized for LNR was $45.4 million for the year ended December 31, 2013.