Employee Benefit Plans (Narrative) (Details) (USD $)	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 30, 2006	Apr. 30, 2003
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum Amount Of Stock-Based Compensation Cost Capitalized	$ 500,000	$ 500,000	$ 500,000
Share Based Compensation Arrangement By Share Based Payment Award, Aggregate Option And Employee Stock Purchase Plan, Grants In Period, Weighted Average Grant Date Fair Value	$ 12.04	$ 13.29	$ 13.99
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Intrinsic Value	9,000,000	2,900,000	3,700,000
Options granted, vesting term (in years)	4 years
Non-cash stock-based compensation	20,014,000	17,462,000	14,372,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	8,400,000	2,300,000	3,000,000
Maximum Percentage Contribution Of Salary By Employees	100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	50.00%
Defined Contribution Plan Maximum Contribution By Employer Value	6,000
Defined Contribution Plan, Cost Recognized	1,000,000	1,000,000	700,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	3,400,000	4,200,000	8,100,000
Total unrecognized compensation	11,000,000
Weighted-average period of recognition of stock based compensation (in days)	2 years 3 months 29 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Total Fair Value	10,000,000	13,000,000	11,100,000
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation	17,400,000
Weighted-average period of recognition of stock based compensation (in days)	2 years 7 months 27 days
2006 Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance				2,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	8,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options, Conversion Ratio	1.58
Number of shares reserved for future grant (in shares)	2,034,455
2006 Long Term Incentive Plan [Member] | First Tranche [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum Percentage Of Exercise Price Granted To Ten Percentage Of Shareholders				110.00%
Options granted, vesting term (in years)				12 months	4 years
Term Of Stock Appreciation Rights From Date Of Grant				10 years
2006 Long Term Incentive Plan [Member] | Remaining Tranche [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting term (in years)				3 years
2006 Long Term Incentive Plan [Member] | Minimum [Member] | RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting term (in years)	3 years
Period of Measuring the Achievement of Personal Goals	12 months
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future grant (in shares)	200,000
Maximum Percentage of compensation contributed by employees (in percentage)	10.00%
Purchase percentage of stock at fair market value (in percentage)	85.00%
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date	15.00%
Non-cash stock-based compensation	$ 523,000	$ 420,000	$ 371,000