Debt Summary of Redemption Percentages (Details) (Senior Unsecured Notes Due April 2023, Senior Notes)	Mar. 31, 2013
Senior Unsecured Notes Due April 2023 | Senior Notes
Debt Instrument Redemption [Line Items]
Debt Instrument, Redemption Price, Percentage, 2018	102.563%
Debt Instrument, Redemption Price, Percentage, 2019	101.708%
Debt Instrument, Redemption Price, Percentage, 2020	100.854%
Debt Instrument, Redemption Price, Percentage, 2021 and thereafter	100.00%