Long-Term Obligations and Commitments (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Jan. 31, 2007	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Long-term obligations
Total		$ 218,840,000	$ 154,407,000
Less: current portion		(3,390,000)	(5,645,000)
Total Long-Term Obligations		145,573,000	148,762,000
Principal amount of convertible notes		178,780,000
Accrued interest payable on the notes		9,941,000
Non-cash interest expense related to the amortization of the debt discount		8,553,000	7,795,000	7,107,000
2 5/8 percent convertible subordinated notes
Long-term obligations
Total		141,448,000	132,895,000
Debt instrument, stated interest rate (as a percent)	2.625%	2.625%	2.625%
Debt offering	162,500,000
Proceeds raised net of issuance cost	157,100,000
Issuance costs	5,400,000
Number of shares to be issued upon debt conversion	11.1
Conversion price (in dollars per share)	$ 14.63
Principal amount of convertible notes		162,500,000	162,500,000
Accrued interest payable on the notes		1,600,000	1,600,000
Fair value of convertible notes		151,100,000	162,300,000
Nonconvertible debt borrowing rate (as a percent)		9.30%
Non-cash interest expense related to the amortization of the debt discount		8,600,000	7,800,000	7,100,000
2 5/8 percent convertible subordinated notes | February 15, 2012 and February 14, 2013
Long-term obligations
Redemption price as a percentage of principal		100.75%
2 5/8 percent convertible subordinated notes | February 15, 2013 and February 14, 2014
Long-term obligations
Redemption price as a percentage of principal		100.375%
2 5/8 percent convertible subordinated notes | February 15, 2014 and thereafter
Long-term obligations
Redemption price as a percentage of principal		100.00%
Long-term financing liability for leased facility
Long-term obligations
Total		69,877,000	10,147,000
Equipment Financing Arrangement
Long-term obligations
Total		5,325,000	9,440,000
Maximum borrowing capacity for equipment purchases		18,400,000
Draw down period (in years)		3
Interest rate swap period, used to calculate interest		3Y
Percentage added to interest rate swap		4.00%
Additional principal amount drawn during the period		1,600,000
Principal drawn down amount		18,300,000
Weighted average interest rate (as a percent)		6.19%
Capital Lease | Office Equipment
Long-term obligations
Amount outstanding		656,000	773,000
Debt instrument, stated interest rate (as a percent)		5.14%	5.14%
Capital Lease
Capital lease period (in years)		5
Net book value of office equipment		585,000	705,000
Accumulated depreciation included in net book value		228,000	65,000
Leases and other obligations
Long-term obligations
Total		$ 2,190,000	$ 1,925,000