Stock-Based Compensation (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 80,153,000	$ 68,138,000	$ 51,983,000
Stock based compensation expenses related to modification of the vesting and exercise terms for a certain employee's equity awards		1,100,000
Capitalized stock-based compensation expense	1,600,000
Number of shares issuable under stock incentive plan	14,300,000
Accelerated recognition of stock-based compensation expense, retirement eligibility	14,800,000	7,800,000
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Weighted average grant date fair value (in dollars per share)	$ 14.86	$ 19.05	$ 17.46
Intrinsic value of stock options exercised	58,000,000	42,100,000	59,500,000
Total unrecognized compensation expense	32,100,000
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	56,600,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years 0 months 0 days
Total unrecognized compensation expense	76,300,000
Expected recognition of stock award compensation expense weighted average period in years	2 years 0 months 0 days
Total fair value of restricted stock units vested during period	58,600,000
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock purchase plan employee discount	15.00%
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	81,000	78,000	88,000
Weighted average prices per share for the ESPP	$ 70.48	$ 64.74	$ 51.59
Employee stock purchase plan offering, expense recognition period, months	6 months
Employee stock purchase plan, fair value per share (in dollars per share)	$ 14.83	$ 13.42	$ 13.64
Employee stock purchase plan, shares remain reserved for future issuance	3,400,000
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years