Summary of Significant Accounting Policies (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended				1 Months Ended	12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 31, 2013	Jun. 30, 2012 Chief Executive Officer [Member]	Dec. 31, 2012 Employees and Eligible Directors [Member]	Dec. 31, 2011 Employees and Eligible Directors [Member]	Dec. 31, 2011 Cumulative impact of prior period reclassification adjustment [Member]	Dec. 31, 2011 Impact of revision on cash flows [Member]	Dec. 31, 2010 Impact of revision on cash flows [Member]
Revision [Abstract]
Impact of revision																								$ 7.9	$ 5.7	$ 2.2
Cash Distributions [Abstract]
Subsequent cash distribution, declaration date	Feb. 12, 2013
Subsequent cash distribution, amount	42.1
Subsequent cash distribution, distribution declared (in dollars per unit)	$ 0.40
Subsequent cash distribution, distribution date	Mar. 14, 2013
Subsequent cash distribution, date of record	Feb. 22, 2013
Non-cash real estate charge	38.9		168.1
Total cash distributions per Unit paid to unitholders (in dollars per unit)	$ 0.40	[1],[2]	$ 0.36	[1],[2]	$ 0.21	[1]	$ 0.26	[1]	$ 0.12	[1],[3]	$ 0.26	[1]	$ 0.34	[1]	$ 0.42	[1]	$ 0.95	$ 1.44	$ 1.51
Long-Term Incentive Compensation Plans [Abstract]
One-time, non-cash deferred compensation charge									587.1
Percentage of unrecognized long-term incentive incentive compensation expense recognized (in hundredths)									100.00%									100.00%
Long-term incentive compensation awards expense									159.9									159.9
Reclassified liability to partners' capital									130.3									130.3
Vesting period of options																	3 years
Holding units purchased in period (in units)																	15,700,000	13,500,000
Dollar amount paid for holding units acquired																	238.0	220.8
Open-market purchases of holding units (in units)																	12,300,000	11,100,000
Dollar amount paid for open-market purchases of holding units																	$ 182.3	$ 192.1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted holding unit awards to employees (in units)																	6,500,000	8,700,000			2,700,000	12,100,000	1,700,000
Unallocated holding units remaining in the consolidated Rabbi Trust (in units)	17,900,000																17,900,000			12,000,000
Options to buy holding units outstanding, number (in units)	8,553,345																8,553,345
Options outstanding and exercisable, number (in units)	4,237,915																4,237,915

[1] Declared and paid during the following quarter.

[2] The third and fourth quarter 2012 distributions exclude the impact of AllianceBernstein's $168.1 million and $38.9 million, respectively, non-cash real estate charges.

[3] The fourth quarter 2011 distribution excludes the impact of AllianceBernstein's $587.1 million one-time, non-cash deferred compensation charge.