Stock-Based Compensation (Stock Option Activity) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Number of Shares
Outstanding at December 31, 2014 (shares)	7,186
Granted (shares)	471
Exercised (shares)	(957)
Forfeited or expired (shares)	(366)
Outstanding at June 30, 2015 (shares)	6,334	7,186
Exercisable at June 30, 2015 (shares)	3,884
Weighted- Average Exercise Price Per Share
Outstanding at December 31, 2014 (usd per share)	$ 35.82
Granted (usd per share)	42.59
Exercised (usd per share)	27.87
Forfeited or expired (usd per share)	37.62
Outstanding at June 30, 2015 (usd per share)	37.43	$ 35.82
Exercisable at June 30, 2015 (usd per share)	$ 37.12
Additional Disclosures
Weighted average remaining contractual term of outstanding options (in years)	4 years 3 months	4 years 3 months
Weighted average remaining contractual term of options exercisable at end of period	3 years 6 months
Aggregate intrinsic value of options outstanding	$ 70,928	$ 31,514
Aggregate intrinsic value of options exercisable at end of period	$ 45,050