Convertible Senior Notes (Capped Call) (Details) shares in Millions, $ in Millions	Mar. 31, 2018 USD ($) $ / Unit shares
Debt Disclosure [Abstract]
Notional amount \| $	$ 37.2
Strike price (in dollars per share)	113.75
Derivative, cap price (in dollars per share)	153.13
Derivative, number of shares covered (in shares) \| shares	3.5

Derivative, Number Of Shares Covered

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- References

No definition available.

+ Details

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- Definition

The cap rate on a price risk derivative such as a cap or collar. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

+ References

No definition available.

+ Details

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1A

+ Details

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- Definition

The strike price on the price risk option contract such as a put option or a call option.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13(Column A)(Footnote 3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13(Column E))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5

+ Details

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