Employee Benefit Plans - Schedule of Fair Value of Plan Assets Measured on a Recurring Basis (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	$ 246	$ 237
Common collective trusts
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	146	150
Corporate bonds (S&P rating of A or higher)
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	16	15
Corporate bonds (S&P rating of lower than A)
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	30	24
US Treasury and Government
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	38	33
Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	15	14
Municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	1	1
Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 1 | Common collective trusts
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 1 | Corporate bonds (S&P rating of A or higher)
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 1 | Corporate bonds (S&P rating of lower than A)
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 1 | US Treasury and Government
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 1 | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 1 | Municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	246	237
Level 2 | Common collective trusts
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	146	150
Level 2 | Corporate bonds (S&P rating of A or higher)
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	16	15
Level 2 | Corporate bonds (S&P rating of lower than A)
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	30	24
Level 2 | US Treasury and Government
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	38	33
Level 2 | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	15	14
Level 2 | Municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	1	1
Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 3 | Common collective trusts
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 3 | Corporate bonds (S&P rating of A or higher)
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 3 | Corporate bonds (S&P rating of lower than A)
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 3 | US Treasury and Government
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 3 | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	0	0
Level 3 | Municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Assets at Fair Value	$ 0	$ 0