Long-Term Debt and Other Liabilities - Additional Information (Detail) $ / shares in Units, shares in Millions			3 Months Ended		6 Months Ended
	Mar. 03, 2015 USD ($) $ / shares shares	Nov. 02, 2010 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) Trading_day shares	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Proceeds received from the issuance of the convertible notes					$ 361,940,000
Amortization of deferred financing costs			$ 1,105,000	$ 861,000	1,889,000	$ 1,697,000
Debt issuance costs			16,903,000		16,903,000		$ 11,296,000
Forward stock repurchase transactions amount					$ 140,000,000
Forward stock repurchase transaction, shares | shares					7.2
Total debt			571,442,000		$ 571,442,000		310,252,000
Letters of Credit [Member]
Debt Instrument [Line Items]
Credit facility/letters of credit amount outstanding			7,874,000		7,874,000		7,874,000
3.75% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount of Convertible Notes	$ 361,900,000		361,900,000		361,900,000
Interest rate	3.75%
Option granted to initial purchasers	$ 60,000,000
Maturity date	Mar. 01, 2020
Additional paid-in-capital	$ 100,000,000
Convertible Notes, carrying amount of liability component	261,900,000		$ 266,473,000		$ 266,473,000
Effective interest rate on convertible notes			11.50%		11.50%
Proceeds received from the issuance of the convertible notes	361,900,000
Convertible Notes, unamortized discount			$ 95,500,000		$ 95,500,000
Loan origination fees	$ 10,400,000
Amortization of deferred financing costs			300,000		400,000
Debt issuance costs			7,100,000		$ 7,100,000
Conversion rate	41.9274
Principal amount	$ 1,000
Conversion price | $ / shares	$ 23.85
Multiples of principal amount	$ 1,000
Debt instrument redemption price, percentage	100.00%
Forward stock repurchase transactions amount	$ 140,000,000
Forward stock repurchase transaction, shares | shares	7.2
Forward stock repurchase transaction, settlement date	Mar. 01, 2020
3.75% Convertible Senior Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Percentage of common share price over conversion price for conversion					130.00%
Common stock price trading days | Trading_day					20
Common stock price consecutive trading days					30 days
3.75% Convertible Senior Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Common stock price trading days | Trading_day					5
Common stock price consecutive trading days					5 days
Debt instrument redemption price, percentage					98.00%
3.75% Convertible Senior Notes [Member] | Issuance Costs [Member]
Debt Instrument [Line Items]
Additional paid-in-capital	$ 2,900,000
Issuance cost recorded to deferred financing costs	7,500,000
3.75% Convertible Senior Notes [Member] | Institutional Buyers [Member]
Debt Instrument [Line Items]
Principal amount of Convertible Notes	340,000,000
Principal amount of Convertible Notes	$ 21,900,000
Amended and Restated Senior Term Facility [Member]
Debt Instrument [Line Items]
Maturity date					Mar. 21, 2018
Loan origination fees					$ 22,200,000
Amortization of deferred financing costs			800,000	$ 900,000	1,500,000	$ 1,700,000
Debt issuance costs			9,800,000		9,800,000		11,300,000
Total debt			$ 304,969,000		304,969,000		309,244,000
Principal payment					1,700,000
Non lender fees					$ 4,100,000
Percentage used for mandatory prepayment					50.00%
Percentage of prepayment					25.00%
Mandatory prepayment					$ 0
Voluntary prepayment percentage			3.00%		3.00%
Voluntary prepayment percentage			3.00%		3.00%
Amended and Restated Senior Term Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio					3.25
Leverage ratio					2.0
Amended and Restated Senior Term Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio					3.25
Leverage ratio					2.0
Amended and Restated Senior Term Facility [Member] | Tranche B-1 Loans [Member]
Debt Instrument [Line Items]
Interest rate			11.25%		11.25%
Amount of credit facility agreement			$ 248,000,000		$ 248,000,000
Amended and Restated Senior Term Facility [Member] | Tranche B-1 Loans [Member] | Interest Rate [Member]
Debt Instrument [Line Items]
Libor rate loan margin					9.75%
Base rate floor					2.50%
Base rate loan margin					8.75%
Amended and Restated Senior Term Facility [Member] | Tranche B-1 Loans [Member] | London Interbank Offered Rate (LIBOR) [Member] | Interest Rate [Member]
Debt Instrument [Line Items]
Statutory rate floor					1.50%
Amended and Restated Senior Term Facility [Member] | Tranche B-2 Loans [Member]
Debt Instrument [Line Items]
Interest rate			7.50%		7.50%
Amount of credit facility agreement			$ 75,000,000		$ 75,000,000
Amended and Restated Senior Term Facility [Member] | Tranche B-2 Loans [Member] | Interest Rate [Member]
Debt Instrument [Line Items]
Libor rate loan margin					6.50%
Base rate floor					2.00%
Base rate loan margin					5.50%
Amended and Restated Senior Term Facility [Member] | Tranche B-2 Loans [Member] | London Interbank Offered Rate (LIBOR) [Member] | Interest Rate [Member]
Debt Instrument [Line Items]
Statutory rate floor					1.00%
Alaska Facility [Member]
Debt Instrument [Line Items]
Interest rate		10.00%
Amount of credit facility agreement		$ 4,100,000
Total debt							$ 1,008,000
Credit facility, termination date					2015-04
Payment period for principal amounts outstanding		6 years