Long-Term Debt and Credit Facility, Textuals (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended									12 Months Ended					12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Convertible Notes Days	Mar. 29, 2010 Convertible Notes	Dec. 31, 2013 Call Options	Dec. 31, 2013 Warrant Transactions	Dec. 31, 2012 Warrant Transactions	Mar. 30, 2010 Warrant Transactions	Dec. 31, 2013 Senior Notes	Dec. 31, 2012 Senior Notes	May 23, 2012 Senior Notes	Dec. 31, 2013 Line of Credit	Dec. 31, 2013 Letter of Credit	Dec. 31, 2013 Minimum	Dec. 31, 2013 Maximum	Dec. 31, 2013 On or after June 1, 2016 Senior Notes	Dec. 31, 2013 On or after June 1, 2018 Senior Notes	Dec. 31, 2013 Prior to June 1, 2015 Senior Notes	Dec. 31, 2013 On or after June 1, 2015 but prior to June 1, 2016 Senior Notes	Dec. 31, 2013 Change in control Senior Notes
Debt Instruments
Principal amount of notes	$ 225,000,000	$ 225,000,000	$ 225,000,000			$ 175,000,000							$ 225,000,000
Interest rate						4.50%							8.25%
Debt issuance, percentage of principal amount													100.00%
Interest expense											19,400,000	11,800,000
Effective interest rate	8.60%	8.60%			11.00%
Redemption price percentage of principal amount																		104.125%	100.00%	108.25%	100.00%	101.00%
Percentage of original principal amount that may be redeemed																				35.00%
Conversion rate of common stock shares per $1,000 of principal amount					20.7903
Principal amount in conversion feature					1,000
Conversion price of note	$ 48.10	$ 48.10
Payment of quarterly cash dividends	$ 0.30	$ 1.20	$ 1.00	$ 0.96												$ 0.24
Threshold percentage of stock price trigger for conversion					130.00%
Threshold trading days for conversion					20
Threshold consecutive trading days for conversion					30 days
Amount of notes converted					0
Common stock sold related to option counterparties net share-settled warrants								3.6	3.6	3.6
Exercise price of call options							$ 48.10
Exercise price per share of Warrants								61.08	61.31
Line of Credit Facility [Abstract]
Maximum borrowing capacity	300,000,000	300,000,000													60,000,000		350,000,000
Percentage of eligible accounts receivable for borrowing base	85.00%	85.00%
Percentage of eligible inventory for borrowing base	65.00%	65.00%
Percentage of net orderly liquidation value of eligible inventory	85.00%	85.00%
Percent of eligible machinery and equipment for borrowing base	85.00%	85.00%
Available borrowing capacity	260,100,000	260,100,000														30,000,000
Outstanding line of credit														0	(7,000,000)
Remaining available borrowing capacity	$ 253,100,000	$ 253,100,000
Interest on line of credit	4.00%	4.00%
Fixed Charge Coverage Ratio		1.1:1.0