Debt - 3.75% Convertible Senior Notes - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2009	Jul. 31, 2013 3.75% Convertible Senior Notes [Member]	Dec. 31, 2013 3.75% Convertible Senior Notes [Member]	Dec. 31, 2013 8% Percent Senior Notes [Member]
Debt Instrument [Line Items]
Convertible notes, Outstanding amount							$ 360,000,000
Maturity date for Notes							Oct. 01, 2014
First semi-annual interest payment date							April 1
Second semi-annual interest payment date							October 1
Conversion rate per $ 1,000 principal of convertible notes							46.7774
Conversion price per share							$ 21.38
Common Stock principal amount of convertible notes							1,000
Minimum trading days period for closing price of Company's common stock to be issued on conversion of debt							20 days
Maximum trading days period for closing price of Company's common stock to be issued on conversion of debt							30 days
Minimum percentage of increase in conversion price per share of common stock on the last trading day under circumstance one of converting the convertible notes							120.00%
Principal amount of convertible notes to be considered for trading price under circumstance two of converting the convertible notes		1,000
Minimum percentage of the last reported sale price of the product under circumstance two of converting the convertible notes		98.00%
Minimum trading days		5 days
Maximum trading days		10 days
Percentage of Purchase price equal to the principal amount of the convertible notes		100.00%
Debt discount and increase in paid in capital							68,000,000
Transaction costs allocated between liability and equity components							10,000,000
Interest rate of Senior Notes							3.75%	8.00%
Effective interest rate of convertible notes							8.43%
Cash Interest expense relating to interest coupon on Convertible Notes		12,400,000	13,500,000	13,500,000
Non-cash interest expense related to the amortization of the debt		13,817,000	13,793,000	12,695,000
Cancellation of Convertible notes						54,700,000
Aggregate consideration for cancellation of convertible notes						98,600,000
Common Shares surrendered by counter party						0.2
Value of convertible notes converted by a holder						1,200,000
Face amount of outstanding debt							304,100,000
Loss on extinguishment on debt	(4,200,000)	(4,181,000)					(4,200,000)
Reduction in stockholder's equity due to repurchase and conversion transactions							43,500,000
Strike price of purchased option		21.38
Purchased options number of shares		14.2
Cost of purchased option					76,700,000
Purchased options expiration date		Oct. 01, 2014
Approximate number of common stock share which can be purchased under warrants		14.3
Exercise price of common stock		25.65					25.65
Proceeds from issuance of common stock warrants					43,700,000
Net proceeds of convertibles notes after deductions					$ 317,100,000
Maturity year of note							2014	2013