Income Taxes - Operating Loss Carryforwards (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 43
Federal [Member] | Tax Year 2026 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	9
Federal [Member] | Tax Year 2027 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	9
Federal [Member] | Tax Year 2028 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	14
Federal [Member] | Tax Year 2029 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	11
State [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	21
State [Member] | Tax Years 2020 - 2024 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	1
State [Member] | Tax Years 2025 - 2029 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	16
State [Member] | Tax Year 2030 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 4