Stock-Based Compensation (Narrative) (Details) (USD $)	12 Months Ended			60 Months Ended	12 Months Ended							12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011	Dec. 31, 2011 Stock Options Plans [Member] years	Dec. 31, 2010 Stock Options Plans [Member]	Dec. 31, 2009 Stock Options Plans [Member]	Dec. 31, 2011 Restricted Stock Units [Member] years	Dec. 31, 2010 Restricted Stock Units [Member]	Dec. 31, 2009 Restricted Stock Units [Member]	May 16, 2007 Maximum [Member]	Dec. 31, 2011 Maximum [Member] Stock Options Plans [Member]	Dec. 31, 2011 Maximum [Member] Restricted Stock Units [Member]	Dec. 31, 2011 Minimum [Member] Stock Options Plans [Member]	Dec. 31, 2011 Minimum [Member] Restricted Stock Units [Member]
Share Based Compensation Arrangement by Share Based Payment Award [Line Items]
Number of common stock reserved for issuance											3,200,000
Expiration year of 2007 Plan	2017
Vesting period (years)												5 years	5 years	3 years	3 years
Option awards contractual term (years)					10
Common stock to non-employee directors under the incentive plan	3,000	4,000	3,000
Stock repurchase program authorized share amount	15,000,000			15,000,000
Common stock repurchased, shares		6,000		11,518,000
Common stock repurchased, value				$ 335,110.00
Common stock repurchased price per share		$ 56.94
Weighted-average grant-date fair value of options granted	$ 25.39	$ 19.10	$ 9.17
Total intrinsic value of options exercised	1,148,000	1,714,000	809,000
Recognized stock-based compensation costs					1,885,000	2,436,000	4,552,000	8,186,000	4,262,000	5,009,000
Recognized stock-based compensation costs, net of tax					1,194,000	1,543,000	2,884,000	5,186,000	2,700,000	3,173,000
Pre-tax unrecognized compensation expense					$ 1,937,000			$ 11,394,000
Recognized expense over a weighted-average period, years					1.4			3.4