Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Taxes [Line Items]
Unrecognized tax benefits	$ 0	$ 0
Net operating loss carryforwards	346,600,000
Tax credit carryforwards	31,365,000	26,365,000
Increases in the valuation allowance	$ 61,600,000	$ 27,400,000	$ 42,400,000
Minimum [Member]
Income Taxes [Line Items]
Net operating loss expiration dates	2018
Tax credit carryforwards expiration dates	2021
Tax years subject to future examination for federal income taxes	1998
Maximum [Member]
Income Taxes [Line Items]
Net operating loss expiration dates	2031
Tax credit carryforwards expiration dates	2031
Tax years subject to future examination for federal income taxes	2011