Share-Based Compensation (Details 1) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Stock option activity in shares and weighted average price
Options outstanding, beginning of period, weighted average price	$ 32.46
Options outstanding, beginning of period, shares	1,375,281	1,400,000
Options granted, weighted average price	$ 32.39
Options granted, shares	336,092
Options canceled, weighted average price	$ 41.19
Options canceled, shares	(32,610)
Options exercised, weighted average price	$ 15.92
Options exercised, shares	(70,297)
Options oustanding, end of period, weighted average price	$ 32.97	$ 32.44
Options outstanding, end of period, shares	1,608,466	1,400,000
Options exercisable, end of period	$ 32.16
Options exercisable, end of period, shares	1,013,829