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Fair Value Measurements (Carrying Values and Estimated Fair Values of Financial Liabilities) (Details) - USD ($) $ in Thousands | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Short-term Debt |  | $ 302,000 |  | $ 0
Short-term Debt, Fair Value |  | 252,141 |  | 0
Finance lease liabilities |  | 622 |  | 737
Long-term debt |  | 550,577 |  | 550,597
Long-term debt, fair value |  | 612,020 |  | 659,272
Unamortized debt issuance costs |  | (3,618) |  |
Seven Point Twenty Five Percent Senior Notes [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Long-term debt, fair value |  | 61,134 |  | 66,365
Unamortized debt issuance costs |  | (180) |  |
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 |  | 49,911 |  | 49,910
Six Point Seventy Percent Senior Notes [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Long-term debt, fair value |  | 118,561 |  | 123,104
Unamortized debt issuance costs |  | (346) |  |
Six Point Seventy Percent Senior Notes [Member] | Reported Value Measurement [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Long-term debt |  | 99,485 |  | 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 |  | 316,400 |  | 357,025
Unamortized debt issuance costs |  | (3,092) |  |
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 |  | 294,177 |  | 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 |  | 25,261 |  | 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 |  | 25,260 |  | 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 |  | 65,404 |  | 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 |  | 553,573 |  | 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 |  | (3,618) |  | (3,687)
Zero Point Seventy Eight Percent Borrowing from FHLBNY Due September 14, 2020. [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Short-term Debt |  | 100,000 |  | 0
Short-term Debt, Fair Value |  | 100,096 |  | 0
Unamortized debt issuance costs |  | 0 |  |
Zero Point Seventy Eight Percent Borrowing from FHLBNY Due September 14, 2020. [Member] | Reported Value Measurement [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Short-term Debt |  | 100,000 |  |
Zero Point Sixty Eight Percent Borrowing from FHLBNY Due September 18, 2020. [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Short-term Debt |  | 85,000 |  | 0
Short-term Debt, Fair Value |  | 85,039 |  | 0
Unamortized debt issuance costs |  | 0 |  |
Zero Point Sixty Eight Percent Borrowing from FHLBNY Due September 18, 2020. [Member] | Reported Value Measurement [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Short-term Debt |  | 85,000 |  |
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 |  | 67,006 |  | 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 |  |
Two Point Two Hundred and Fourty Four Percent Borrowing from Bank of Montreal Due September 24, 2020 [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Short-term Debt |  | 50,000 | [1] | 0
Short-term Debt, Fair Value |  | 0 |  | 0
Unamortized debt issuance costs |  | 0 |  |
Two Point Two Hundred and Fourty Four Percent Borrowing from Bank of Montreal Due September 24, 2020 [Member] | Reported Value Measurement [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Short-term Debt | [1] | 50,000 |  |
Short-term Debt [Member] |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Short-term Debt |  | 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 |  | $ 302,000 |  |
[1] | Total short-term debt includes our $50 million line of credit borrowing. As there is no scheduled or definitive repayment plan for this borrowing as of March 31, 2020, the fair value cannot be calculated and the borrowing is not classified in the fair value hierarchy table below.

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- Definition Present value of lessee's discounted obligation for lease payments from finance lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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