Long-term Incentive Compensation Plans (Details) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 01, 2013	Jan. 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Long-term Incentive Compensation Plans [Abstract]
Holding units purchased in period (in units)			15,000	300,000	200,000	1,300,000
Dollar amount paid for holding units acquired			$ 400,000	$ 7,400,000	$ 4,100,000	$ 27,000,000
Open-market purchases of holding units (in units)				300,000		1,100,000
Dollar amount paid for open-market purchases of holding units				7,200,000		23,200,000
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted holding unit awards to employees (in units)		6,500,000
Decrease in units outstanding (in units)	13,100,000				103,245
Units issued upon options exercised (in units)					705,310
Proceeds from stock options exercised					$ 12,026,000	$ 13,281,000
Employees and Eligible Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted holding unit awards to employees (in units)					400,000	6,800,000