Stock based Compensation (Details 1) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning of year	5,499
Granted	396
Exercised	1,458	993	1,011
Forfeited and expired	(630)
Outstanding, end of year	3,807	5,499
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Outstanding, weighted average exercise price	$ 28.29	$ 28.24
Granted, weighted-average exercise price	$ 29.19
Exercised, weighted-average exercise price	$ 27.28
Forfeited and expired, weighted-average exercise price	$ 30.68
Outstanding, end of year, weighted-average contractual life, Options	2.5
Outstanding, end of year, aggregate intrinsic value, options	$ 4,841
Vested or expected to vest, end of year, number of shares	3,559
Vested or expected to vest, end of year, weighted-average exercise price	$ 28.37
Vested or expected to vest, end of year, weighted-average contractual life	2.4
Vested or expected to vest, end of year, aggregate intrinsic value	4,424
Exercisable, end of year, number of shares	2,397
Exercisable, end of year, weighted-average exercise price	$ 29.00
Exercisable, end of year, weighted-average contractual life	1.4
Exercisable, end of year, aggregate intrinsic value	$ 2,600