Business Combinations, Asset Acquisitions and Dispositions (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Dec. 31, 2010
Changes to goodwill
Goodwil, gross	$ 20,522.6	$ 20,440.2		$ 20,532.5
Accumulated impairment losses	(3,240.1)	(3,235.6)		(3,235.6)
Goodwill, net	17,282.5	17,204.6	17,232.0	17,296.9
Deconsolidation		(42.8)
Acquisitions	48.9
Purchase price adjustments		(4.5)
Impairments	(4.5)
Other adjustments (primarily foreign currency)	33.5	(45.0)
Divested Operations
Changes to goodwill
Goodwil, gross	181.3	181.3		181.3
Accumulated impairment losses	(181.3)	(181.3)		(181.3)
Retail and Alliance Services
Changes to goodwill
Goodwil, gross	14,071.8	14,022.9		14,065.7
Accumulated impairment losses	(1,106.5)	(1,106.5)		(1,106.5)
Goodwill, net	12,965.3	12,916.4		12,959.2
Deconsolidation		(42.8)
Acquisitions	48.9
Financial Services
Changes to goodwill
Goodwil, gross	3,451.4	3,451.4		3,451.4
Accumulated impairment losses	(1,399.7)	(1,395.2)		(1,395.2)
Goodwill, net	2,051.7	2,056.2		2,056.2
Impairments	(4.5)
International
Changes to goodwill
Goodwil, gross	2,641.1	2,607.6		2,657.1
Accumulated impairment losses	(375.6)	(375.6)		(375.6)
Goodwill, net	2,265.5	2,232.0		2,281.5
Purchase price adjustments		(4.5)
Other adjustments (primarily foreign currency)	33.5	(45.0)
All Other and Corporate
Changes to goodwill
Goodwil, gross	177.0	177.0		177.0
Accumulated impairment losses	$ (177.0)	$ (177.0)		$ (177.0)

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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+ Details

- Definition

The aggregate amount of goodwill acquired in the period and allocated to the reportable segment. The value is stated at fair value based on the purchase price allocation.

+ References+ Details

- Definition

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

+ References

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+ Details

- Definition

Write-off of the carrying amount of goodwill associated with all or a portion of a reporting unit that is sold in the period.

+ References+ Details