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Debt And Liquidity Debt And Liquidity (Senior Notes) (Details) - Senior Notes [Member] - USD ($) | Dec. 31, 2016 | Nov. 20, 2012
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Debt Instrument [Line Items] |  |
Principal amount issued |  | $ 300,000,000
Stated interest rate |  | 6.375%
Redemption price percentage of principal prior to November 15, 2016 |  | 100.00%
Repurchase percentage price of aggregate principal due to change in control |  | 101.00%
Minimum [Member] |  |
Debt Instrument [Line Items] |  |
Unpaid indebtness after maturity or acceleration | $ 50,000,000 |
Unpaid judgment or decree | $ 50,000,000 |

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