Employee Benefit Plans (Narrative) (Details) (USD $)	12 Months Ended							1 Months Ended			1 Months Ended						7 Months Ended	12 Months Ended			1 Months Ended						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2012 Restricted Stock Units (RSUs) [Member]	Dec. 31, 2011 Restricted Stock Units (RSUs) [Member]	Dec. 31, 2010 Restricted Stock Units (RSUs) [Member]	Apr. 30, 2000 2000 Stock Option Plan [Member]	Apr. 30, 2003 2003 Stock Plan [Member]	Dec. 31, 2012 2003 Stock Plan [Member]	Apr. 30, 2003 2003 Stock Plan [Member] Stock Options [Member]	Jun. 30, 2012 2006 Long Term Incentive Plan [Member]	Jul. 31, 2010 2006 Long Term Incentive Plan [Member]	Jun. 30, 2008 2006 Long Term Incentive Plan [Member]	Apr. 30, 2006 2006 Long Term Incentive Plan [Member]	Dec. 31, 2012 2006 Long Term Incentive Plan [Member]	Dec. 31, 2012 2006 Long Term Incentive Plan [Member] Restricted Stock Units (RSUs) [Member]	Dec. 31, 2012 Employee Stock Purchase Plan [Member]	Dec. 31, 2011 Employee Stock Purchase Plan [Member]	Dec. 31, 2010 Employee Stock Purchase Plan [Member]	Apr. 30, 2003 Full Vesting Period [Member] 2003 Stock Plan [Member] Stock Options [Member]	Apr. 30, 2006 Full Vesting Period [Member] 2006 Long Term Incentive Plan [Member] Stock Options [Member]	Apr. 30, 2003 First Tranche [Member] 2003 Stock Plan [Member] Stock Options [Member]	Apr. 30, 2003 First Tranche [Member] 2006 Long Term Incentive Plan [Member] Stock Options [Member]	Apr. 30, 2003 Remaining Tranche [Member] 2003 Stock Plan [Member] Stock Options [Member]	Apr. 30, 2003 Remaining Tranche [Member] 2006 Long Term Incentive Plan [Member] Stock Options [Member]	Dec. 31, 2012 Minimum [Member] 2006 Long Term Incentive Plan [Member]	Dec. 31, 2012 Minimum [Member] 2006 Long Term Incentive Plan [Member] Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total number of common stock reserved for issuance								7,350,000	750,000						2,500,000			387,058
Stock option contractual life from grant date (in years)								10 years			10 years
Minimum percentage of exercise price granted to 10% of shareholders								110.00%			110.00%				110.00%
Options granted, vesting term (in years)	4 years							4 years													4 years	4 years	12 months	12 months	3 years	3 years		3 years
Term of stock appreciation rights from date of grant (in years)															10 years
Period of measuring the achievement of personal goals																											12 months
Number of shares transferred under stock option plan									615,290
Number of shares reserved for future grant (in shares)									1,365,290	55,513						2,695,054
Percentage of expiration of stock options on resale restriction									25.00%
Additional authorization of shares for future issuance												3,000,000	1,500,000	2,500,000
RSUs conversion ratio																	1.58
Maximum percentage of compensation contributed by employees (in percentage)																		10.00%
Purchase percentage of stock at fair market value (in percentage)																		85.00%
Compensation expense	$ 14,372,000	$ 13,762,000	$ 12,201,000															$ 371,000	$ 354,000	$ 236,000
Total intrinsic value of options exercised	8,100,000	21,800,000	16,900,000
Total fair value of options vested	11,100,000	9,800,000	9,100,000
Percentage of discount on purchase of stock at fair market value																		15.00%
Total intrinsic value of RSUs vested					3,700,000	4,400,000	3,100,000
Total fair value of RSU's vested					3,000,000	2,600,000	2,600,000
Weighted average estimated fair value of options including options granted under ESPP	$ 13.99	$ 14.29	$ 10.80
Maximum amount of stock-based compensation cost capitalized	250,000	250,000	250,000
Total unrecognized compensation				24,100,000	1,700,000
Weighted-average period of recognition of stock based compensation (in days)				1 year 4 months 17 days	0 years 9 months 14 days
Maximum 401k contribution percentage of salary by employees	100.00%
Company 401K matching contribution percent	50.00%
Maximum employer 401K match contributions	6,000
Expense recognized related to the 401(k)	$ 689,000	$ 0	$ 0