Impairment of Long-lived Assets - Components of the Net Investment in Long-term Leases (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Oct. 31, 2000
Property, Plant and Equipment [Abstract]
Estimated residual value of leased assets	$ 685	$ 1,465	$ 1,600
Less: unearned income	328	767
Net investment in long-term leases	$ 357	$ 698