Share-Based Compensation (Details 1) (USD $)	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Stock option activity in shares and weighted average price
Options outstanding, beginning of period	$ 32.46
Options outstanding, beginning of period, shares	1,375,281	1,400,000
Options granted	$ 32.39
Options granted, shares	336,092
Options canceled	$ 47.15
Options canceled, shares	(23,733)
Options exercised	$ 17.02
Options exercised, shares	(57,107)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 32.78	$ 32.39
Options outstanding, end of period, shares	1,630,533	1,400,000
Options exercisable, end of period	$ 31.87
Options exercisable, end of period, shares	1,035,896