Long-term Incentive Compensation Plans (Details) (USD $)	1 Months Ended		3 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Long-term Incentive Compensation Plans [Abstract]
Maximum percentage of award an employee can elect to allocate to deferred cash (in hundredths)			50.00%
Maximum amount of deferred cash			$ 250,000
Number of business days used in calculation			5 days
Restricted Holding Units awarded to employees (in units)	6,500,000	8,700,000	6,600,000	9,100,000
Reclassified liability to partners' capital			129,200,000
Holding Units purchased in periods (in units)			1,000,000	4,500,000
Dollar amount paid for Holding Units acquired			19,600,000	66,000,000
Open-market purchases of Holding Units (in units)			800,000	4,300,000
Dollar amount paid for open-market purchases of Holding Units			16,000,000	63,200,000
Unallocated Holding Units remaining in rabbi trust (in units)			12,500,000
Units issued upon exercise of options (in units)			392,528
Proceeds from stock options exercised			$ 6,600,000