Fair Value Measurements (Carrying Value and Estimated Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Carrying Amount [Member]
Long-term debt	$ 550,597	$ 439,540
Carrying Amount [Member] \| Seven Point Twenty Five Percent Senior Notes [Member]
Long-term debt	49,910	49,907
Carrying Amount [Member] \| Six Point Seventy Percent Senior Notes [Member]
Long-term debt	99,480	99,462
Carrying Amount [Member] \| Five Point Eight Hundred Seventy Five Percent Senior Notes [Member]
Long-term debt	0	185,000
Carrying Amount [Member] \| Five Point Three Hundred Seventy Five [Member]
Long-term debt	294,157	0
Carrying Amount [Member] \| One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Long-term debt	25,000	25,000
Carrying Amount [Member] \| One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Long-term debt	25,000	25,000
Carrying Amount [Member] \| Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Long-term debt	60,000	60,000
Carrying Amount [Member] \| Long Term Debt Excluding Issuance Costs [Member]
Long-term debt	553,547	444,369
Carrying Amount [Member] \| Unamortized Debt Issuance Costs [Member]
Unamortized Debt Issuance Costs	(3,687)	(4,829)
Carrying Amount [Member] \| Finance lease obligation [Member]
Finance Lease, Liability	737	0
Fair Value [Member]
Long-term Debt, Fair Value	659,272	448,622
Fair Value [Member] \| Seven Point Twenty Five Percent Senior Notes [Member]
Long-term Debt, Fair Value	66,365	57,032
Fair Value [Member] \| Six Point Seventy Percent Senior Notes [Member]
Long-term Debt, Fair Value	123,104	107,075
Fair Value [Member] \| Five Point Eight Hundred Seventy Five Percent Senior Notes [Member]
Long-term Debt, Fair Value	0	177,230
Fair Value [Member] \| Five Point Three Hundred Seventy Five [Member]
Long-term Debt, Fair Value	357,025	0
Fair Value [Member] \| One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Long-term Debt, Fair Value	24,901	24,218
Fair Value [Member] \| One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Long-term Debt, Fair Value	24,875	24,162
Fair Value [Member] \| Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Long-term Debt, Fair Value	$ 63,002	$ 58,905

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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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
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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

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