Long-term Incentive Compensation Plans (Details) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 01, 2013	Jan. 31, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Long-term Incentive Compensation Plans [Abstract]
Holding units purchased in period (in units)			100,000	800,000	200,000	2,100,000
Dollar amount paid for holding units acquired			$ 1,300,000	$ 16,300,000	$ 5,400,000	$ 43,300,000
Open-market purchases of holding units (in units)				800,000		1,900,000
Dollar amount paid for open-market purchases of holding units				15,300,000		38,500,000
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				188,215
Units issued upon options exercised (in units)					753,622
Proceeds from stock options exercised					$ 12,849,000	$ 13,859,000
Employees and Eligible Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted holding unit awards to employees (in units)					800,000	6,900,000