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Fair Value Measurements (Carrying Values and Estimated Fair Values of Financial Liabilities) (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | --- | ---
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Short-term Debt | $ 167,000 |  | $ 0
Short-term Debt, Fair Value | 167,055 |  | 0
Finance lease liabilities | 424 |  | 737
Long-term debt | 550,566 |  | 550,597
Long-term debt, fair value | 682,253 |  | 659,272
Unamortized debt issuance costs | (3,485) |  |
Seven Point Twenty Five Percent Senior Notes [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt, fair value | 67,350 |  | 66,365
Unamortized debt issuance costs | (170) |  |
Seven Point Twenty Five Percent Senior Notes [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt | 49,913 |  | 49,910
Six Point Seventy Percent Senior Notes [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt, fair value | 130,651 |  | 123,104
Unamortized debt issuance costs | (329) |  |
Six Point Seventy Percent Senior Notes [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt | 99,495 |  | 99,480
Five Point Three Hundred Seventy Five Senior Notes [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt, fair value | 365,756 |  | 357,025
Unamortized debt issuance costs | (2,986) |  |
Five Point Three Hundred Seventy Five Senior Notes [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt | 294,219 |  | 294,157
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt, fair value | 25,255 |  | 24,901
Unamortized debt issuance costs | 0 |  |
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt | 25,000 |  | 25,000
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt, fair value | 25,269 |  | 24,875
Unamortized debt issuance costs | 0 |  |
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt | 25,000 |  | 25,000
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt, fair value | 67,972 |  | 63,002
Unamortized debt issuance costs | 0 |  |
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt | 60,000 |  | 60,000
Long Term Debt Excluding Issuance Costs and Finance Lease Obligations [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term debt | 553,627 |  | 553,547
Unamortized Debt Issuance Costs [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Unamortized debt issuance costs | (3,485) |  | (3,687)
Zero Point Thirty Six Percent Borrowing from FHLBNY Due November 16, 2020 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Short-term Debt | 100,000 |  | 0
Short-term Debt, Fair Value | 100,005 |  | 0
Unamortized debt issuance costs | 0 |  |
Zero Point Thirty Six Percent Borrowing from FHLBNY Due November 16, 2020 [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Short-term Debt | 100,000 |  | 0
Zero Point Fifty Eight Percent Borrowing from FHLBI Due December 14, 2020. [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Short-term Debt | 67,000 |  | 0
Short-term Debt, Fair Value | 67,050 |  | 0
Unamortized debt issuance costs | 0 |  |
Zero Point Fifty Eight Percent Borrowing from FHLBI Due December 14, 2020. [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Short-term Debt | 67,000 |  | 0
Short-term Debt [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Short-term Debt | 167,000 | $ 302,000 | 0
Unamortized debt issuance costs | 0 |  |
Short-term Debt [Member] | Reported Value Measurement [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Short-term Debt | $ 167,000 |  | $ 0

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