Stock-Based Compensation (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Dec. 31, 2009
Stock options / awards
Stock-based compensation expense	$ 2,900,000	$ 3,400,000	$ 5,200,000	$ 6,500,000
Stock options
Stock option / award activity
Options outstanding at the beginning of the period (in shares)			3,722,656	3,693,697
Granted (in shares)			781,000	846,000
Exercised (in shares)			(44,398)	(95,064)
Forfeited (in shares)			(322,424)	(364,953)
Options outstanding at the end of the period (in shares)	4,136,834	4,079,680	4,136,834	4,079,680
Number of shares available for grant (in shares)	3,233,548	1,220,742	3,233,548	1,220,742	1,477,072
Total shares reserved at the end of period (in shares)	7,370,382	5,300,422	7,370,382	5,300,422
Options exercisable at the end of period (in shares)	2,685,545	2,806,552	2,685,545	2,806,552
WEIGHTED-AVERAGE EXERCISE PRICE
Options outstanding at the beginning of the period (in dollars per option)			$ 33.29	$ 36.43
Granted (in dollars per option)	$ 16.52	$ 23.30	$ 16.52	$ 23.30
Exercised (in dollars per option)	$ 11.97	$ 7.80	$ 11.97	$ 7.80
Forfeited (in dollars per option)	$ 55.57	$ 50.70	$ 55.57	$ 50.70
Options outstanding at the end of the period (in dollars per option)	$ 28.61	$ 33.10	$ 28.61	$ 33.10
Options exercisable at the end of period (in dollars per option)	$ 33.83	$ 37.84	$ 33.83	$ 37.84
WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (in years)
Options outstanding at the end of the period	2.9	3.2	2.9	3.2	2.8	3.1
Options exercisable at the end of the period			2.2	2.8
AGGREGATE INTRINSIC VALUE
Options outstanding at the end of the period	885,000	1,501,000	885,000	1,501,000
Options exercisable at the end of period	577,000	1,055,000	577,000	1,055,000
Stock options / awards
Stock-based compensation expense	1,200,000	1,400,000	2,200,000	2,900,000
Intrinsic values of stock options exercised	29,000	113,000	284,000	1,400,000
Director Plan
Stock option / award activity
Number of shares available for grant (in shares)					21,975
Director Plan.
Stock-based compensation
Number of shares authorized for issuance to each director			3,000
Period after which each new non-employee director will receive stock award (in days)			30 days
Stock option / award activity
Number of shares available for grant (in shares)	176,000		176,000
Stock options / awards
Stock-based compensation expense	102,000	172,000	210,000	289,000
Restricted stock units
Stock options / awards
Stock-based compensation expense	$ 1,600,000	$ 1,900,000	$ 2,700,000	$ 3,400,000
Restricted stock units
Restricted stock units at the beginning of the period (in shares)			727,317	609,812
Shares awarded (in shares)			305,000	404,000
Shares vested (in shares)			(304,492)	(225,496)
Shares forfeited (in shares)			(60,000)	(50,999)
Restricted stock units at the end of the period (in shares)	667,825	737,317	667,825	737,317
Outstanding restricted shares vesting schedule
Outstanding restricted stock unit awards, vesting in 2011 (in shares)	10,000		10,000
Outstanding restricted stock unit awards, vesting in 2012 (in shares)	345,494		345,494
Outstanding restricted stock unit awards, vesting in 2013 (in shares)	210,664		210,664
Outstanding restricted stock unit awards, vesting in 2014 (in shares)	101,667		101,667