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

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-SubTopic 470
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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

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Debt and Credit Facilities 6.0% Senior Notes due 2024 (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Jun. 30, 2016	Dec. 31, 2018	Sep. 30, 2018	Dec. 22, 2016	Jun. 21, 2016
5.625% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Senior Notes, Noncurrent		$ 495,056	$ 494,915	$ 500,000
Debt Instrument, Interest Rate, Stated Percentage		5.625%		5.625%
Unamortized Debt Issuance Expense		$ 4,944	5,085
6.0% Senior Notes due 2024 [Member]
Debt Instrument [Line Items]
Senior Notes, Noncurrent		$ 298,297	$ 298,220		$ 300,000
Debt Instrument, Interest Rate, Stated Percentage		6.00%	6.00%		6.00%
Proceeds from Issuance of Long-term Debt	$ 297,500
Unamortized Debt Issuance Expense		$ 1,703	$ 1,780
Debt Instrument, Redemption Price, Percentage		100.00%