Long-Term Debt - Senior Notes Net Interest Expense (Details) - Senior Notes - 6.125% Senior Notes - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Interest Expense and Amortization of Debt Issue Costs
Interest expense	$ 8,697	$ 8,680	$ 17,390	$ 17,357
Debt issue cost amortization	321	321	642	640
Debt discount amortization	275	258	546	513
Total	$ 9,293	$ 9,259	$ 18,578	$ 18,510

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of the cost of borrowed funds accounted for as interest expense.

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