Convertible Notes, Long-Term Debt and Credit Facility (Additional Disclosures) (Details) (USD $)	0 Months Ended		1 Months Ended		12 Months Ended					0 Months Ended	1 Months Ended	12 Months Ended	0 Months Ended			1 Months Ended	12 Months Ended		0 Months Ended		12 Months Ended		12 Months Ended			0 Months Ended
	Mar. 31, 2010	Feb. 14, 2008	Jun. 30, 2012	Nov. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Feb. 29, 2008	Feb. 11, 2008	Mar. 31, 2010 Term loan [Member]	Jun. 30, 2011 Term loan [Member]	Dec. 31, 2012 Term loan [Member]	Dec. 31, 2012 2008 Notes [Member]	Jun. 25, 2012 2008 Notes [Member]	Feb. 14, 2008 2008 Notes [Member]	May 31, 2011 2008 Notes [Member]	Dec. 31, 2012 2008 Notes [Member]	Mar. 31, 2010 2008 Notes [Member]	Mar. 31, 2010 Senior credit facility [Member]	Jan. 05, 2012 2010 Notes [Member]	Dec. 31, 2012 2010 Notes [Member]	Mar. 31, 2010 2010 Notes [Member]	Dec. 31, 2012 Exchange agreement [Member]	Mar. 31, 2010 Exchange agreement [Member]	Mar. 31, 2010 Convertible Note [Member]	Mar. 31, 2010 Annual interest rate 12.5% [Member] Term loan [Member]
Line of Credit Facility [Line Items]
Debt instrument, principal amount															$ 115,000,000
Term loan, face amount										40,000,000.0
Convertible notes, interest rate															5.25%						5.25%
Convertible notes maturity date										Nov. 01, 2012					Feb. 15, 2028						Feb. 15, 2028
Nonconvertible debt borrowing interest rate													11.50%				11.50%
Expected term for accretion of associated debt discount (in years)																	5 years
Contractual call/put options, exercisable date																	Feb. 15, 2013
Discount on notes															27,800,000
Deferred tax liability on notes						1,939,000									10,600,000
Percentage of original principal amount of notes plus accrued and unpaid interest equalized repurchase														102.00%						104.95%
Debt instrument, maturity date										Nov. 01, 2012					Feb. 15, 2028						Feb. 15, 2028
Senior credit facility, value of common stock converted	50																							2,000,000
Convertible notes for each $1,000 principal amount, amount of notes exchanged																		40,000,000
Convertible notes for each $1,000 principal amount, amount of aggregate consideration																						36,000,000
Redeemable price as a percentage of outstanding principal note amount																	100.00%
Amount of notes exchanged																4,500,000				36,000,000
Loss on the extinguishment of debt											2,100,000		900,000	1,000,000		1,100,000				(5,400,000)
Cash premium loss recognized on conversion of debt					3,710,000	5,295,000	4,946,000						300,000	300,000						1,800,000
Contingent interest percentage on principal amount of notes, minimum																							120.00%
Contingent interest payable rate																							0.50%
Common stock, shares issued					53,123,978	51,957,652	36,753,891																		1,568,867
Convertible notes for each $1,000 principal amount, number of shares																559,007
Convertible notes, interest payment period																					6 months
Periodic prinicpal payments										1,000,000
Term loan, annual interest rate																										12.50%
Convertible notes for each $1000 principal amount, principal amount of 2010 Notes converted					1,000													1,000				900
Senior note commitment fee																			7,300,000
Return of borrowed shares under share-based, shares			659,340	701,102	659,340	701,102
Credit facility, commitment fee percentage												50.00%											50.00%
Capital lease obligations					1,784,000	1,642,000
Convertible Notes Long Term Debt and Credit Facility (Textual) [Abstract]
Effective tax rate		38.00%			35.00%	35.00%	35.00%
Convertible notes for each $1,000 principal amount, volume-weighted average price of common stock rate	95.00%
Convertible notes for each $1,000 principal amount, number of preceding trading days	10 days				5 days
Convertible notes for each $1,000 principal amount, number of shares					43.9560
Convertible notes for each $1,000 principal amount, conversion price per share					$ 22.75
Assumed rate of accretion on notes	9.90%
Convertible notes for each $1,000 principal amount, third-party transaction costs	800,000
Share lending agreement, number of common stock shares loaned					3,800,000				3,800,000
Own share lending arrangement nominal loan fee per share								$ 0.0001
Borrowed shares outstanding					2,439,558
Share lending agreement, fair value					500,000
Common shares not subject to the share lending arrangement, fair value					29,800,000
Notes repurchased													$ 50,300,000	$ 15,000,000			$ 50,300,000