Share-Based Compensation - (Details) (Stock Options [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options [Member]
Summary of outstanding stock options
Number of options outstanding, beginning balance	2,991,000	3,045,000	6,809,000
Weighted average exercise price, beginning balance	$ 28.48	$ 28.39	$ 26.47
Number of options, exercised	(1,347,000)	(44,000)	(2,253,000)
Weighted average exercise price options, exercised	$ 27.97	$ 22.52	$ 21.75
Number of options, forfeited	(4,000)	(10,000)	(1,511,000)
Weighted average exercise price options, forfeited	$ 25.45	$ 27.82	$ 29.66
Number of options outstanding, ending balance	1,640,000	2,991,000	3,045,000
Weighted average exercise price, ending balance	$ 28.91	$ 28.48	$ 28.39
Number of options exercisable at end of year	1,640,000	2,991,000	2,841,000
Weighted average exercise price, exercisable	$ 28.91	$ 28.48	$ 29.79