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Fair Value Measurements - Recurring Measurements of Liabilities (Details) - USD ($) $ in Thousands | Dec. 31, 2016 | Aug. 31, 2016 | Dec. 31, 2015
--- | --- | --- | ---
5% Convertible Senior Notes due 2017 |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |
Stated interest rate (in hundredths) | 5.00% |  |
2% Convertible Senior Notes due 2020 |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |
Stated interest rate (in hundredths) | 2.00% |  |
Senior Notes | 5.75% Senior Notes due 2023 |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |
Stated interest rate (in hundredths) | 5.75% | 5.75% |
9% Convertible Junior Subordinated Debentures due 2063 |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |
Stated interest rate (in hundredths) | 9.00% |  |
Carrying Value |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |
FHLB Advance | $ 155,000 |  |
5% Notes | 144,789 |  | $ 331,546
2% Notes | 204,672 |  | 490,755
5.75% Notes | 417,406 |  |
9% Debentures | 256,872 |  | 389,522
Total financial liabilities | 1,178,739 |  | 1,211,823
Fair Value | Significant Other Observable Inputs (Level 2) |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |
FHLB Advance | 151,905 |  |
5% Notes | 147,679 |  | 345,616
2% Notes | 308,605 |  | 701,955
5.75% Notes | 445,987 |  |
9% Debentures | 323,040 |  | 455,067
Total financial liabilities | $ 1,377,216 |  | $ 1,502,638

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