Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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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Fair value amount of debt instrument that was repurchased.

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Face (par) amount of the original debt instrument that was repurchased.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

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Fair Value Inputs, Swap Rate Term

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Debt - Additional Information (Details) - USD ($)			1 Months Ended	3 Months Ended
Debt - Additional Information (Details) - USD ($)	Mar. 03, 2017	Aug. 21, 2013	Mar. 31, 2017	Sep. 30, 2017	Oct. 01, 2016	Jul. 01, 2017	Mar. 22, 2017
Debt details
Loss on extinguishment of debt				$ 3,600,000	$ 0
1.00% Senior Convertible Notes \| Convertible Notes
Debt details
Interest rate on senior convertible notes				1.00%
Aggregate principal amount of convertible debt	$ 400,000,000						$ 60,000,000
Proceeds from debt, net of issuance costs			$ 451,100,000
Discount rate	4.80%
Derivative, term of contract	7 years
Fair market value of convertible debt				$ 463,100,000		$ 481,700,000
Amount outstanding				$ 460,000,000		460,000,000
0.625% Senior Convertible Notes \| Convertible Notes
Debt details
Interest rate on senior convertible notes		0.625%		0.625%
Aggregate principal amount of convertible debt		$ 650,000,000.0
Proceeds from debt, net of issuance costs		$ 636,300,000
Discount rate		5.40%
Derivative, term of contract		5 years
Redemption percentage		100.00%
Fair market value of convertible debt				$ 488,000,000		676,100,000
Expected remaining term				10 months 15 days
Principal amount of debt repurchased				$ 146,500,000.0
Repurchase of debt				162,000,000
Loss on extinguishment of debt				3,600,000
Amount outstanding				$ 463,500,000		$ 610,000,000