Debt - Additional Information (Detail)		12 Months Ended
	Apr. 13, 2016 USD ($) shares $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Mar. 15, 2016 USD ($)
Debt Instrument [Line Items]
Long-term debt, due in 2017		$ 106,000,000
Long-term debt, due in 2018		10,300,000
Long-term debt, due in 2019		1,300,000
Long-term debt, due in 2020		1,300,000
Long-term debt, due in 2021		180,300,000
Long-term debt, thereafter		800,000
Capital leases, due in 2017		3,000,000
Capital leases, due in 2018		2,400,000
Capital leases, due in 2019		1,300,000
Capital leases, due in 2020		1,300,000
Capital leases, due in 2021		1,300,000
Capital leases, thereafter		800,000
Cash paid for interest		22,100,000	$ 14,400,000	$ 13,200,000
Capitalized interest expense		3,000,000	3,100,000	4,000,000
Charge recognized for retirement of debt		4,000,000	0	0
Payment of capped call transactions		27,300,000	0	$ 0
Aggregate other debt default amount to violate covenant, minimum		50,000,000
Maximum
Debt Instrument [Line Items]
Availability under the facility		$ 18,750,000
Percentage of lenders' commitments under facility		12.50%
Dividends on capital stock		$ 22,500,000
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity under the credit agreement		150,000,000
Borrowings outstanding		0
Letters of credit outstanding		11,300,000
Availability under the facility		102,500,000
Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity under the credit agreement		$ 100,000,000
Convertible Senior Notes Due 2021 Issued April 2016
Debt Instrument [Line Items]
Convertible senior notes, principal amount	$ 23,500,000.0
Senior Notes | Convertible Senior Notes Due 2021 Issued March 2016
Debt Instrument [Line Items]
Convertible senior notes, principal amount					$ 190,000,000
Senior Notes | 5.50% convertible senior notes due March 1, 2021
Debt Instrument [Line Items]
Senior notes, interest rate	5.50%	5.50%
Convertible senior notes, principal amount	$ 213,500,000.0	$ 213,500,000.0
Effective interest rate	9.50%
Conversion rate for notes	0.1024249
Convertible shares total (in shares) | shares	21,867,716
Initial conversion price (in dollars per share) | $ / shares	$ 9.76	$ 12.75
Payment of capped call transactions	$ 27,300,000
Conversion premium on the notes	22.50%	60.00%
Debt discount	$ 33,600,000	$ 34,400,000.0
Interest expense, debt		14,500,000
Contractual interest coupon		9,200,000
Amortization of debt discount		4,300,000
Amortization of debt issuance costs		1,000,000
Senior Notes | 6.25% senior notes due August 15, 2017
Debt Instrument [Line Items]
Aggregate principal amount retired		$ 115,000,000
Senior notes, interest rate		6.25%
Charge recognized for retirement of debt		$ 4,000,000
Premium paid		3,600,000
Write-off of issuance costs		400,000
Convertible senior notes, principal amount		95,000,000.0	210,000,000.0
Debt discount		$ 300,000.0	$ 1,800,000.0