Debt Long-Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Feb. 04, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Credit Agreement	$ 948,000		$ 965,500
Total long-term debt	1,439,874		1,462,031
6% Senior notes
Debt Instrument [Line Items]
Principal	0	$ 500,000	500,000
Unamortized discount	0		(3,469)
6% Senior notes \| Fair value inputs, Level 2 \| Carrying Value
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	0		496,531
Five Percent Senior Notes Due Two Thousand Twenty Eight [Member]
Debt Instrument [Line Items]
Principal	500,000		0
Unamortized discount	(8,126)		0
Five Percent Senior Notes Due Two Thousand Twenty Eight [Member] \| Fair value inputs, Level 2 \| Carrying Value
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	$ 491,874		$ 0

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

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Amount, after accumulated amortization, of debt discount.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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