Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Assets
Available-for-sale securities	$ 1,535	$ 1,554
Recurring basis
Assets
Available-for-sale securities	1,535	1,554
Total Assets	1,535	1,554
Liabilities
Derivative Liabilities, at Fair Value, Net	97	86
Guarantees	13	12
Total Liabilities	110	98
U.S. treasury bonds
Assets
Available-for-sale securities	10	10
U.S. treasury bonds | Recurring basis
Assets
Available-for-sale securities	10	10
Other U.S. and non-U.S. government bonds
Assets
Available-for-sale securities	98	94
Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Available-for-sale securities	98	94
Corporate bonds
Assets
Available-for-sale securities	662	693
Corporate bonds | Recurring basis
Assets
Available-for-sale securities	662	693
Asset-backed securities
Assets
Available-for-sale securities	103	105
Asset-backed securities | Recurring basis
Assets
Available-for-sale securities	103	105
U.S. governmental agency | Recurring basis
Assets
Available-for-sale securities	281	294
Residential
Assets
Available-for-sale securities	14	15
Residential | Recurring basis
Assets
Available-for-sale securities	14	15
Commercial
Assets
Available-for-sale securities	64	67
Commercial | Recurring basis
Assets
Available-for-sale securities	64	67
Large capitalization value
Assets
Available-for-sale securities	256	233
Large capitalization value | Recurring basis
Assets
Available-for-sale securities	256	233
Smaller company growth
Assets
Available-for-sale securities	47	43
Smaller company growth | Recurring basis
Assets
Available-for-sale securities	47	43
Level 1 | Recurring basis
Assets
Available-for-sale securities	313	286
Total Assets	313	286
Liabilities
Derivative Liabilities, at Fair Value, Net	0	0
Guarantees	0	0
Total Liabilities	0	0
Level 1 | U.S. treasury bonds | Recurring basis
Assets
Available-for-sale securities	10	10
Level 1 | Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Available-for-sale securities	0	0
Level 1 | Corporate bonds | Recurring basis
Assets
Available-for-sale securities	0	0
Level 1 | Asset-backed securities | Recurring basis
Assets
Available-for-sale securities	0	0
Level 1 | U.S. governmental agency | Recurring basis
Assets
Available-for-sale securities	0	0
Level 1 | Residential | Recurring basis
Assets
Available-for-sale securities	0	0
Level 1 | Commercial | Recurring basis
Assets
Available-for-sale securities	0	0
Level 1 | Large capitalization value | Recurring basis
Assets
Available-for-sale securities	256	233
Level 1 | Smaller company growth | Recurring basis
Assets
Available-for-sale securities	47	43
Level 2 | Recurring basis
Assets
Available-for-sale securities	1,222	1,268
Total Assets	1,222	1,268
Liabilities
Derivative Liabilities, at Fair Value, Net	97	86
Guarantees	0	0
Total Liabilities	97	86
Level 2 | U.S. treasury bonds | Recurring basis
Assets
Available-for-sale securities	0	0
Level 2 | Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Available-for-sale securities	98	94
Level 2 | Corporate bonds | Recurring basis
Assets
Available-for-sale securities	662	693
Level 2 | Asset-backed securities | Recurring basis
Assets
Available-for-sale securities	103	105
Level 2 | U.S. governmental agency | Recurring basis
Assets
Available-for-sale securities	281	294
Level 2 | Residential | Recurring basis
Assets
Available-for-sale securities	14	15
Level 2 | Commercial | Recurring basis
Assets
Available-for-sale securities	64	67
Level 2 | Large capitalization value | Recurring basis
Assets
Available-for-sale securities	0	0
Level 2 | Smaller company growth | Recurring basis
Assets
Available-for-sale securities	0	0
Level 3 | Recurring basis
Assets
Available-for-sale securities	0	0
Total Assets	0	0
Liabilities
Derivative Liabilities, at Fair Value, Net	0	0
Guarantees	13	12
Total Liabilities	13	12
Level 3 | U.S. treasury bonds | Recurring basis
Assets
Available-for-sale securities	0	0
Level 3 | Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Available-for-sale securities	0	0
Level 3 | Corporate bonds | Recurring basis
Assets
Available-for-sale securities	0	0
Level 3 | Asset-backed securities | Recurring basis
Assets
Available-for-sale securities	0	0
Level 3 | U.S. governmental agency | Recurring basis
Assets
Available-for-sale securities	0	0
Level 3 | Residential | Recurring basis
Assets
Available-for-sale securities	0	0
Level 3 | Commercial | Recurring basis
Assets
Available-for-sale securities	0	0
Level 3 | Large capitalization value | Recurring basis
Assets
Available-for-sale securities	0	0
Level 3 | Smaller company growth | Recurring basis
Assets
Available-for-sale securities	$ 0	$ 0