Debt - Additional Information (Detail)	1 Months Ended	12 Months Ended						12 Months Ended			12 Months Ended							12 Months Ended		0 Months Ended		12 Months Ended				12 Months Ended
	Jun. 30, 2013 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2014 Prior Credit Facility [Member] USD ($)	Jun. 28, 2013 Letter of Credit [Member] USD ($)	Jun. 28, 2013 Line of Credit [Member] USD ($)	Dec. 31, 2014 Senior Secured Revolving Facility And / Or Term Loan Facility [Member] USD ($)	Dec. 31, 2014 Senior Secured Revolving Facility And / Or Term Loan Facility [Member] Maximum [Member]	Dec. 31, 2014 Senior Secured Revolving Facility And / Or Term Loan Facility [Member] Minimum [Member]	Dec. 31, 2014 Credit Agreement On Two Thousand And Thirteen [Member] USD ($)	Dec. 31, 2014 1.25% Cash Convertible Senior Notes [Member] USD ($)	Dec. 31, 2013 1.25% Cash Convertible Senior Notes [Member] USD ($)	Dec. 31, 2012 1.25% Cash Convertible Senior Notes [Member] USD ($)	Jun. 18, 2013 1.25% Cash Convertible Senior Notes [Member] USD ($)	Dec. 31, 2014 1.25% Cash Convertible Senior Notes [Member] Maximum [Member]	Dec. 31, 2014 1.25% Cash Convertible Senior Notes [Member] Minimum [Member]	Dec. 31, 2014 1.25% Cash Convertible Senior Notes [Member] Condition One [Member]	Dec. 31, 2014 1.25% Cash Convertible Senior Notes [Member] Condition Two [Member] USD ($)	Jun. 28, 2013 Term Loan Facility [Member] USD ($)	Jun. 28, 2013 Senior Secured Revolving Facility [Member] USD ($)	Dec. 31, 2014 Senior Secured Revolving Facility [Member] USD ($)	Dec. 31, 2014 Senior Secured Revolving Facility [Member] US Dollars [Member] USD ($)	Dec. 31, 2014 Senior Secured Revolving Facility [Member] British Pounds Sterling [member] USD ($)	Dec. 31, 2014 Senior Secured Revolving Facility [Member] British Pounds Sterling [member] GBP (£)	Dec. 31, 2014 Senior Secured Revolving Facility [Member] Eurocurrency Rate for U.S. Dollars [Member]	Dec. 31, 2014 Senior Secured Revolving Facility [Member] LIBOR [Member] US Dollars [Member]	Dec. 31, 2014 Senior Secured Term Loan [Member] USD ($)
Debt Instrument [Line Items]
Debt instrument principal amount		$ 645,535,000	$ 641,875,000									$ 345,000,000	$ 345,000,000		$ 345,000,000							$ 98,035,000						$ 202,500,000
Proceeds from debt												305,100,000
Repayment of outstanding prior credit facility					300,000,000
Interest payment, terms												Interest on the 1.25% Notes is payable semiannually in arrears on January 1 and July 1 of each year
Debt, Maturity date		Jul. 01, 2020										Jul. 01, 2020
Threshold trading days																		20 days	5 days
Threshold consecutive trading days																		30 days	5 days
Debt instrument conversion price percentage																		130.00%	98.00%
Debt instrument convertible, principal amount												1,000							1,000
Convertible number of equity instrument												58.1869
Conversion price per common stock		$ 17.19										$ 17.19
Repurchase percentage on principal												100.00%
Fair value liability of embedded cash conversion option												82,800,000
Convertible debt instrument remaining discount amortization period												5 years 6 months
Debt instrument, interest rate, effective percentage												5.40%											2.92%	2.87%	2.87%
Debt Instrument, fees and aggregate cost								3,100,000				8,400,000
Debt instrument capitalized amount					5,500,000			4,300,000				8,300,000
Deferred charges capitalized amount outstanding								3,000,000				6,500,000
Accrued and unpaid interest												2,200,000
Payments for 1.25% Call Option	82,800,000	0	82,800,000	0
Proceeds from issuance of warrants, net of issuance costs	51,200,000	0	51,208,000	0
Net cash payment for 1.25% Notes call spread overlay			31,600,000
Credit facility, maximum borrowing capacity																				225,000,000	425,000,000
Senior secured credit facilities term, years																				5 years	5 years
Term Loan repayment, end date																				2018-06
Portion of facility available for issuance of letters of credit						50,000,000
Portion of facility available for issuance of swingline loans							10,000,000
Credit facility, maximum borrowing capacity, foreign currencies																					100,000,000
Aggregate amount of additional credit facilities authorized								250,000,000
Applicable margin for borrowings based on federal funds rate																						0.50%
Senior secured credit facility interest rate spread																										1.00%	2.75%
Initial margin for borrowings based on non-Eurocurrency rate																						1.25%
Initial margin for borrowings based on Eurocurrency rate																						2.25%
Maximum percentage of foreign subsidiary capital stock guaranteeing credit facility		65.00%
Leverage ratio									400.00%							400.00%
Interest coverage ratio										400.00%							400.00%
Secured leverage ratio									300.00%
Debt issue discount, amortized to interest expense		69,614,000	80,849,000					3,800,000				67,276,000	77,529,000
Deferred debt issuance cost written off with previous credit facility		0	3,901,000	0							3,400,000
Amortization of debt issuance costs		2,041,000	3,667,000	5,066,000				500,000				1,180,000	639,000	0
Credit facility, amount borrowed																						98,000,000	82,500,000	15,500,000	10,000,000
Borrowings outstanding in term loan																												202,500,000
Letters of credit outstanding		900,000
Unamortized deferred debt issuance costs		9,500,000
Credit facility, amount available																						$ 325,600,000