Share-Based Compensation (Details 1) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 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	1,500,000
Options granted	$ 32.60
Options granted, shares	323,439
Options canceled	$ 47.15
Options canceled, shares	(17,199)
Options exercised	$ 18.64
Options exercised, shares	(27,116)
Options outstanding, end of period	$ 32.56
Options outstanding, end of period, shares	1,654,405	1,500,000
Options exercisable, end of period	$ 31.45
Options exercisable, end of period, shares	1,065,306