Authorized Shares Of Common And Preferred Stock And Stock-Based Compensation Plans (Narrative) (Details) (USD $)	0 Months Ended	12 Months Ended							12 Months Ended			0 Months Ended	12 Months Ended				12 Months Ended		12 Months Ended		12 Months Ended				12 Months Ended
	May 14, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Incentive Plan (1994) [Member]	Dec. 31, 2004 Incentive Plan (1994) [Member]	Dec. 31, 1997 Incentive Plan (1994) [Member]	May 09, 1994 Incentive Plan (1994) [Member]	Dec. 31, 2013 Incentive Plan (1994) [Member] Minimum [Member]	Dec. 31, 2013 Incentive Plan (1994) [Member] Maximum [Member]	Dec. 31, 2013 Restricted Stock Units [Member]	May 10, 2011 Employee Stock Purchase Plan [Member]	Dec. 31, 2013 Employee Stock Purchase Plan [Member]	Dec. 31, 2013 Employee Stock Purchase Plan [Member] Maximum [Member]	Dec. 31, 2013 Authorized Preferred Stock And Preferred Stock Purchase Rights Plan [Member]	Jan. 21, 2004 Authorized Preferred Stock And Preferred Stock Purchase Rights Plan [Member]	Dec. 31, 2013 Authorized Preferred Stock And Preferred Stock Purchase Rights Plan [Member] Maximum [Member]	May 11, 2010 Restricted Stock Plan [Member]	Dec. 31, 2013 Restricted Stock Plan [Member] Incentive Plan (2005) [Member]	May 10, 2005 Restricted Stock Plan [Member] Incentive Plan (2005) [Member]	Dec. 31, 2013 Restricted Stock Plan [Member] Incentive Plan (2005) [Member] Minimum [Member]	Dec. 31, 2013 Restricted Stock Plan [Member] Incentive Plan (2005) [Member] Maximum [Member]	Dec. 31, 2013 Restricted Stock Plan [Member] Incentive Plan (2010) [Member]	May 11, 2010 Restricted Stock Plan [Member] Incentive Plan (2010) [Member]	Dec. 31, 2013 Restricted Stock Plan [Member] Incentive Plan (2010) [Member] Minimum [Member]	Dec. 31, 2013 Restricted Stock Plan [Member] Incentive Plan (2010) [Member] Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional number of shares reserved for issuance	180,000,000					1,125,000	10,631,250					3,000,000
Common stock, shares authorized		360,000,000	180,000,000
Number of shares reserved for issuance								13,668,750								750,000		3,362,304		4,050,000				3,000,000
Common and preferred stock shares authorized		365,000,000
Preferred stock, par value		$ 0.01	$ 0.01
Common stock, par value		$ 0.01	$ 0.01
Award vesting period, (in years)									5 years	10 years									5 years		3 years	10 years	5 years		3 years	10 years
Expiration period from date options granted					10 years
Aggregate intrinsic value of stock options at exercise		$ 8,300,000	$ 2,400,000	$ 13,000,000
Unrecognized stock-based compensation expense		11,000									89,400,000
Unrecognized stock-based compensation expense, shares		11,765									3,506,562
Unrecognized stock-based compensation expense, weighted average fair value		$ 13.81									$ 26.23
Weighted average period for which unrecognized stock-based compensation expense recognized		6 months 22 days									5 years 5 months 5 days
Weighted-average remaining contractual life of options exercisable		6 months 29 days
Aggregate intrinsic value of stock options		3,900,000
Aggregate intrinsic value of options outstanding		$ 3,700,000
Options granted
Number of shares available for grant																							3,318,042
Percentage of the lower of the market related to purchase of common stock													85.00%
Maximum employee subscription rate														15.00%
Shares of common stock reserved for future employee purchases													1,380,751
Shares issued during the period, in shares													1,191,599
Weighted average grant date fair value, in dollar per share													$ 22.48
Preferred stock, shares authorized		5,000,000	5,000,000
Number of preferred shares declared for each share of common stock outstanding, in shares															1
Portion of a share of Series A Participating Preferred Stock each Right entitles its holder to purchase															0.001
Exercise price of Series A Participating Preferred Stock Rights, in dollar per share															$ 200
Percentage of common stock before rights become exercisable															20.00%
Multiple of original exercise price for which holder is entitled to purchase (in number of times: 2x, 3x, etc.)															2
Redemption price of Series A Participating Preferred Stock															$ 0.01
Preferred stock, shares issued		0	0
Preferred stock, shares outstanding		0	0
Expiration date																	May 10, 2014
Authorized common stock available for repurchase		3,932,245