Stock-Based Compensation (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock-based compensation expense	$ 51,983,000	$ 47,437,000	$ 52,555,000
Stock based compensation expenses related to modification of the vesting and exercise terms for a certain employee's equity awards		3,000,000
Stock-based compensation, equity awards period, years	4 years 0 months 0 days
Number of shares issuable under stock incentive plan	18,600,000
Excess tax benefits from the exercises of employee stock options	6,900,000	3,000,000
Capitalized stock-based compensation expense	2,200,000	3,100,000	0
Share Based Compensation Arrangement By Share Based Payment Award Award Life	10 years
Stock Option [Member]
Weighted average grant date fair value per share	$ 17.46	$ 17.18	$ 15.03
Intrinsic value of stock options exercised	59,500,000	54,600,000	62,700,000
Total unrecognized compensation expense	30,800,000
Expected recognition of stock award compensation expense weighted average period in years	2 years 0 months 0 days
Employee service share-based compensation, cash received from exercise of stock options	50,900,000
Excess tax benefits from the exercises of employee stock options	2,100,000
Restricted Stock [Member]
Total unrecognized compensation expense	68,800,000
Expected recognition of stock award compensation expense weighted average period in years	2 years 0 months 0 days
Fair Value of restricted stock awards vested	(56,300,000)
Employee Stock Purchase Plan [Member]
Common stock purchased during bi-annual offer	85.00%
Employee stock purchase plan offering, expense recognition period, months	0 years 6 months 0 days
Employee purchase shares not exceeding of gross compensation	15.00%
Employee purchase value not exceeding	$ 25,000
Number of shares purchased by employees under the Employee Stock Purchase Plan	87,749	79,049	75,354
Purchased shares fair value, weighted average price per share	$ (51.59)	$ 44.56	$ 34.16
Weighted average fair value per share for the ESPP	$ 13.64	$ 12.18	$ 9.43
Employee stock purchase plan, shares remain reserved for future issuance	3,500,000