Indebtedness (Schedule of Outstanding Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2019		Jan. 01, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt Discount and Unamortized Issuance Cost	$ 10,331
Finance lease liabilities	1,109	[1]	$ 900	$ 0	[1]
Long-term Debt	$ 550,778
Long-term Debt				439,540
Five Point Three Hundred Seventy Five Senior Notes [Member]
Debt Instrument [Line Items]
Interest Rate	5.375%
Original Amount	$ 300,000
Debt Discount and Unamortized Issuance Cost	9,141
Long-term Debt	$ 290,859
Long-term Debt				0
Five Point Eight Hundred Seventy Five Senior Notes [Member]
Debt Instrument [Line Items]
Interest Rate	5.875%
Original Amount	$ 185,000
Debt Discount and Unamortized Issuance Cost	0
Long-term Debt	$ 0
Long-term Debt				180,771
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Debt Instrument [Line Items]
Interest Rate	3.03%
Original Amount	$ 60,000
Debt Discount and Unamortized Issuance Cost	0
Long-term Debt	$ 60,000
Long-term Debt				60,000
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Debt Instrument [Line Items]
Interest Rate	1.56%
Original Amount	$ 25,000
Debt Discount and Unamortized Issuance Cost	0
Long-term Debt	$ 25,000
Long-term Debt				25,000
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Debt Instrument [Line Items]
Interest Rate	1.61%
Original Amount	$ 25,000
Debt Discount and Unamortized Issuance Cost	0
Long-term Debt	$ 25,000
Long-term Debt				25,000
Six Point Seventy Percent Senior Notes [Member]
Debt Instrument [Line Items]
Interest Rate	6.70%
Original Amount	$ 100,000
Debt Discount and Unamortized Issuance Cost	903
Long-term Debt	$ 99,097
Long-term Debt				99,069
Seven Point Twenty Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Interest Rate	7.25%
Original Amount	$ 50,000
Debt Discount and Unamortized Issuance Cost	287
Long-term Debt	$ 49,713
Long-term Debt				$ 49,700

[1] Concurrent with the adoption of ASU 2016-02 discussed in Note 2. "Adoption of Accounting Pronouncements," finance lease obligations are now captured in Long-term debt on our Consolidated Balance Sheets.