Goodwill and Other Intangible Assets - Estimated Aggregate Pre-Tax Amortization Expense Related to Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense remainder of 2013	$ 43
Amortization expense 2014	49
Amortization expense 2015	22
Amortization expense 2016	20
Amortization expense 2017	$ 17