Overview and Summary of Significant Accounting Policies (Details 4) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based compensation
Stock-based compensation expense									$ 35,326,000	$ 26,390,000	$ 22,117,000
Numerator:
Net income (loss) - basic									(187,787,000)	76,110,000	(84,847,000)
Net income (loss) - diluted									(187,787,000)	76,110,000	(84,847,000)
Denominator:
Weighted average common shares outstanding - basic									65,148	63,422	62,618
Dilutive effect of stock options (in shares)										588
Weighted-average common shares outstanding and dilutive potential common shares - diluted									65,148	64,010	62,618
Net income (loss) per share:
Basic (in dollars per share)	$ (0.64)	$ 0.26	$ (1.65)	$ (0.88)	$ 3.40	$ (0.58)	$ (0.86)	$ (0.78)	$ (2.88)	$ 1.20	$ (1.35)
Diluted (in dollars per share)	$ (0.64)	$ 0.25	$ (1.65)	$ (0.88)	$ 3.16	$ (0.58)	$ (0.86)	$ (0.78)	$ (2.88)	$ 1.19	$ (1.35)
Employees
Share-based compensation
Stock-based compensation expense									35,300,000	26,400,000	22,100,000
Net income (loss) includes employee stock-based compensation expense per diluted share (in dollars per share)									$ 0.54	$ 0.41	$ 0.35
Non-employees
Share-based compensation
Stock-based compensation expense									2,600,000	600,000	700,000
Stock-based awards
Share-based compensation
Unrecorded stock-based compensation expense - stock options	53,500,000								53,500,000
Unrecorded stock-based compensation expense, amortization period									2 years 8 months 12 days
Restricted Stock
Share-based compensation
Unrecorded stock-based compensation expense - restricted stock	$ 10,000,000								$ 10,000,000
Unrecorded stock-based compensation expense, amortization period									1 year 3 months 18 days