Debt - Bonds, Term Loan Facility, Convertible Debt (Details) $ / shares in Units, shares in Millions				3 Months Ended			9 Months Ended
	Aug. 17, 2015 USD ($)	Feb. 14, 2014 USD ($)	Feb. 13, 2014 $ / shares shares	Sep. 30, 2015 USD ($) $ / shares	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2015 USD ($) item $ / shares	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Nov. 12, 2014 USD ($)	Feb. 28, 2014 $ / shares shares	Feb. 11, 2014 $ / shares
Debt
Repayments of debt							$ 327,509,000
Loss on debt extinguishment				$ (10,449,000)			$ (10,449,000)
Interest rate (as a percent)				2.50%			2.50%		2.50%
Amount outstanding, net				$ 1,005,161,000			$ 1,005,161,000		$ 495,346,000
Liability component:
Principal				200,000,000			200,000,000
Less: debt discount, net				(27,406,000)			(27,406,000)
Net carrying amount				172,594,000			172,594,000		167,441,000
Fair value of debt				322,100,000			322,100,000
Equity component				38,188,000			38,188,000
Total interest expense recognized
Total interest expense				$ 14,222,000	$ 3,129,000		$ 34,794,000	$ 7,656,000
Convertible Bond Hedge
Common stock covered under convertible bond hedge (in shares) | shares			7.4
Exercise price (in dollars per unit) | $ / shares			$ 27.09
Purchase of convertible bond hedges, net of tax						$ 39,800,000		39,760,000
Warrant Transactions
Number of shares of common stock called by warrants | shares											7.4
Exercise price (in dollars per share) | $ / shares											$ 34.12
Exercise price above last reported sale price of common stock (as a percent)											70.00%
Proceeds from issuance of warrants						$ 25,700,000		25,620,000
Minimum
Debt
Redemption price as a percentage of principal, at any time (as a percent)							25.00%
Convertible Debt
Debt
Aggregate principal amount of debt issued		$ 200,000,000
Interest rate (as a percent)				2.50%			2.50%
Debt term							5 years
Net proceeds from issuance of convertible debt		193,300,000
Fees and expenses		6,700,000
Proceeds used to pay the cost of the bond hedges (after such cost was partially offset by proceeds from the sale of warrants)		14,100,000
Initial conversion rate of common stock per $1000 of principal amount of Notes (in shares)							36.9079
Principal amount used for debt instrument conversion ratio				$ 1,000			$ 1,000
Initial conversion price of convertible notes into common stock (in dollars per share) | $ / shares				$ 27.09			$ 27.09
Liability component:
Net carrying amount				$ 172,600,000			$ 172,600,000
Amount of if convertible value exceed the principal amount							93,300,000
Fair value of debt				$ 322,100,000			$ 322,100,000
Debt issuance costs allocated to equity component		1,300,000
Debt issuance costs allocated to the liability component		$ 5,400,000
Effective interest rate on liability component (as a percent)				7.23%			7.23%
Total interest expense recognized
Contractual interest expense				$ 1,250,000	1,250,000		$ 3,750,000	3,125,000
Amortization of debt issuance costs				253,000	234,000		733,000	564,000
Amortization of debt discount				1,777,000	1,645,000		5,153,000	3,967,000
Total interest expense				3,280,000	$ 3,129,000		$ 9,636,000	$ 7,656,000
Warrant Transactions
Sale price of common stock (in dollars per share) | $ / shares												$ 20.07
Convertible Debt | Debt Instrument Convertible Covenant One [Member]
Debt
Number of days during 30 consecutive trading days in which the closing price of the entity's common stock must exceed or equal the conversion price for the notes to be convertible | item							20
Number of consecutive trading days during which the closing price of the entity's common stock must exceed or equal the conversion price for at least 20 days in order for the notes to be convertible							30 days
Percentage of the closing sales price of the entity's common stock that the conversion price must exceed or be equal in order for the notes to be convertible							130.00%
Convertible Debt | Debt Instrument Convertible Covenant Two [Member]
Debt
Principal amount used for debt instrument conversion ratio				1,000			$ 1,000
Number of consecutive business days after any five consecutive trading day period during the note measurement period							5 days
Number of consecutive trading days before five consecutive business days during the note measurement period							5 days
Convertible Debt | Debt Instrument Convertible Covenant Two [Member] | Maximum
Debt
Percentage of product of the last reported sale price of the entity's common stock and the conversion rate of convertible debt instruments							98.00%
Convertible Debt | Debt Instrument Convertible Covenant Three [Member]
Debt
Principal amount used for debt instrument conversion ratio				$ 1,000			$ 1,000
Number of days during 30 consecutive trading days in which the closing price of the entity's common stock must exceed or equal the conversion price for the notes to be convertible | item							30
2023 Senior Notes
Debt
Aggregate principal amount of debt issued	$ 500,000,000
Interest rate (as a percent)	7.875%			7.875%			7.875%
Percentage of principal amount of debt that may be redeemed utilizing net cash proceeds from certain equity offerings, and provided that a certain percentage of the originally issued debt remains outstanding after such redemption							35.00%
Redemption price as a percentage of principal, which may be redeemed utilizing net cash proceeds from certain equity offerings, and provided that a certain percentage of the originally issued debt remains outstanding after such redemption							107.875%
Redemption price as a percentage of principal, at any time (as a percent)							100.00%
Increase in redemption price of principal							101
Amount outstanding, net				$ 490,108,000			$ 490,108,000
Bridge loan commitment fee							$ 6,800,000
2023 Senior Notes | Minimum
Debt
Percentage of principal amount of debt that must remain outstanding for certain redemption terms to be applicable							65.00%
2015 Term Loan Facility
Debt
Aggregate principal amount of debt issued	$ 350,000,000
Debt term	6 years
Amount outstanding, net				342,459,000			$ 342,459,000
2015 Term Loan Facility | Term Loan
Debt
Debt term	6 years
Maximum borrowing capacity for incremental loans	$ 350,000,000
Amount outstanding, net	342,500,000
Unamortized debt issuance costs	7,300,000
Installment payment amount	$ 4,400,000
Annual mandatory prepayment of debt as a percentage of excess cash flow	50.00%
Percentage of equity interests in domestic subsidiaries pledged as collateral for borrowing (as a percent)	100.00%
Percentage of voting equity interests in direct foreign subsidiaries pledged as collateral for borrowing (as a percent)	65.00%
Percentage of non-voting equity interests in direct foreign subsidiaries pledged as collateral for borrowing (as a percent)	100.00%
Fees and expenses	$ 2,400,000
Liability component:
Debt issuance costs allocated to the liability component	7,300,000
2015 Term Loan Facility | Incremental Loans
Debt
Maximum borrowing capacity for incremental loans	225,000,000
Convertible Notes 2.5 Percent
Debt
Amount outstanding, net				172,594,000			172,594,000		167,441,000
2014 Term Loan Facility
Debt
Aggregate principal amount of debt issued										$ 340,000,000
Repayments of debt	$ 323,000,000
Debt term	5 years
Amount outstanding, net									$ 327,905,000
2014 Term Loan Facility | Term Loan
Debt
Repayments of debt	$ 323,000,000
Loss on debt extinguishment	10,400,000
CBR Acquisition Holdings Corp
Debt
Loss on debt extinguishment				$ 10,400,000			$ 10,400,000
CBR Acquisition Holdings Corp | 2023 Senior Notes | Private Placement
Debt
Aggregate principal amount of debt issued	$ 500,000,000