Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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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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The effective interest rate at the end of the reporting period.

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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.

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Long-Term Debt - Components Table (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Apr. 04, 2017	Jul. 28, 2014
Long-Term Debt
Long-term debt	$ 835,790	$ 917,721
Revolving Credit Facility
Long-Term Debt
Long-term debt	$ 30,930	$ 122,461
Weighted average interest rate, as a percent	3.00%	3.20%
Convertible Senior Notes 1.00 percent due 2020
Long-Term Debt
Long-term debt	$ 260,563	$ 251,973
Interest rate, as a percentage	1.00%	1.00%
Aggregate principle amount	$ 287,500
Unamortized discount and capitalized debt issuance costs	26,937	$ 35,527
Senior Notes 5.125 Percent Due 2022
Long-Term Debt
Long-term debt	$ 248,562	$ 248,038
Interest rate, as a percentage	5.125%	5.125%
Aggregate principle amount	$ 250,000			$ 250,000
Capitalized debt issuance costs	1,400	$ 2,000
Senior Notes 5.50 Percent Due 2025
Long-Term Debt
Long-term debt	$ 295,735	295,249
Interest rate, as a percentage	5.50%
Aggregate principle amount	$ 300,000		$ 300,000
Capitalized debt issuance costs	$ 4,300	$ 4,800