Shareholders' Equity And Stock Incentive Plan (Narrative) (Details) (USD $)	1 Months Ended		12 Months Ended
	Dec. 31, 2010	Apr. 30, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of common stock in an underwritten public offering, value	$ 114,900,000	$ 73,800,000			$ 188,534,000
Issuance of warrants to purchase of common stock			31,983	28,576	57,641
Investments warrants expiration date			Aug. 21, 2017
Investment warrants, exercise price			$ 22.09
Number of stock options, restricted stock and restricted stock units granted, covering, shares, net of forfeitures	414,854		242,854	263,354	414,854	895,463
Liability for stock, stock appreciation rights to be settled in cash			2,300,000
Share-based compensation arrangement by share-based payment award, Options, exercises in period, total intrinsic value			400,000	3,600,000	6,000,000
Employee service share-based compensation, cash received from exercise of stock options			100,000	47,000,000	700,000
Stock Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum issuance of grant awards under Incentive Plan			7,245,000
Number of stock options, restricted stock and restricted stock units granted, covering, shares, net of forfeitures			5,070,325
Restricted Stock Award And Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized			18,600,000
Cash Settled Stock Appreciation Rights Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized			900,000
Issuance of cash stock appreciation rights			193,336	153,801
Liability for cash stock appreciation rights			4,900,000	6,500,000
Liability for cash stock appreciation rights, classified as other accrued liabilities			4,200,000	5,200,000
Liability for cash stock appreciation rights remainder, classified as other long term liabilities			$ 700,000	$ 1,300,000
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized, period for recognition			1 year 10 months 24 days
Underwriter [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock offerings, net of offering costs, shares	3,975,000	3,220,000
Underwritten public offering price	$ 28.90	$ 23.00