Consolidation of a Real Estate Development Company - Revenues and Expenses Recognized in the Partnership's Condensed Consolidated Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue of a consolidated real estate VIE
Land development services	$ 9.7	$ 6.0	$ 71.0	$ 15.8
Investment income	1.2	7.2	2.9	11.4
Revenue of a consolidated real estate VIE	10.9	13.2	73.9	27.2
Interest and other expenses of a consolidated real estate VIE:
Costs of products sold and services rendered	2.5	8.8	45.7	25.3
Interest expense	13.3	8.6	33.6	30.3
Change in fair value of loans payable	3.0	9.1	12.6	35.4
Compensation and benefits	4.3	3.0	9.1	8.5
G&A and other expenses	3.7	8.8	23.4	30.0
Interest and other expenses of a consolidated real estate VIE	$ 26.8	$ 38.3	$ 124.4	$ 129.5