Stock-Based Compensation (Narrative) (Details) (USD $)	12 Months Ended					12 Months Ended				12 Months Ended								12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011 Stock Options [Member] years	Dec. 31, 2010 Stock Options [Member]	Dec. 31, 2009 Stock Options [Member]	Dec. 30, 2011 Stock Options [Member]	Dec. 31, 2011 RSUs [Member] years	Dec. 31, 2010 RSUs [Member]	Dec. 31, 2009 RSUs [Member]	Dec. 30, 2011 RSUs [Member]	Dec. 31, 2011 Employees [Member] Share-Based Compensation Plans [Member]	Dec. 31, 2011 Non-Employee Members [Member] Share-Based Compensation Plans [Member]	Dec. 31, 2011 Corporate Incentive Compensation Plan [Member] RSUs [Member]	Dec. 31, 2011 1994 Long-Term Incentive Plan [Member]	Dec. 31, 2011 1996 Non-Employee Director Stock Option Plan [Member]	Dec. 31, 2011 2004 Long-Term Incentive Plan [Member]	Jul. 31, 2011 2004 Long-Term Incentive Plan [Member]	Mar. 31, 2010 2004 Long-Term Incentive Plan [Member]	Dec. 31, 2011 2006 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option term	ten-year
Compensation percentage of target incentive compensation eligible to be elected and received by employees												50.00%
Percentage on date of grant of equity amount for elected employees on target incentive compensation												50.00%
Vesting percentage of awards for elected employees of target incentive compensation												100.00%
Number of shares outstanding		2,532,000	3,003,000										200,000	70,000	2,952,000			500,000
Value of common stock grantable to employees gross of fair market value of common stock adjustments on date of grant																	$ 70,000
Stock price percentage of fair market value																		85.00%
Stock purchase price percentage on completion date of offering period																		95.00%
Shares remaining for issuance for future equity grants	6,014,000														5,611,000			403,000
Aggregate number of shares issued under plan																		97,000
Shares granted		342,000								593,000	8,000
Weighted-average grant-date fair value of options granted		$ 11.91	$ 12.22	$ 10.15
Aggregate intrinsic value of options exercised		19,400,000	23,800,000	42,800,000
Closing price of common stock					$ 29.40				$ 29.40
Unrecognized stock-based compensation expense		3,600,000				9,600,000
Weighted-average period of recognition of unrecognized stock-based compensation expense (in years)		2.3				2.4
Weighted-average grant-date fair value of stock units granted						$ 30.87	$ 33.90	$ 27.29
Stock units, period of vesting						five years
RSU expected vesting date												March 2012
Vesting percentage of stock units within one year						20.00%
Vesting percentage of stock units within four years following year one						80.00%
Number of units expected to vest						498,000						47,000
Vesting percentage of stock units												100.00%
Fair value of stock units vested						$ 6,400,000	$ 4,500,000	$ 3,000,000
Minimum stock-based compensation arrangement vesting period, in years	four
Maximum stock-based compensation arrangement vesting period, in years	five
Number of authorized shares																5,000,000