Stock based Compensation (Details 1) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward
Outstanding, beginning of year	3,807
Granted	240
Exercised	2,079	1,458	1,404
Forfeited and expired	(454)
Outstanding, end of year	1,514	3,807
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstrac
Outstanding, weighted average exercise price	$ 27.33	$ 28.29
Granted, weighted-average exercise price	$ 31.88
Exercised, weighted-average exercise price	$ 28.86
Forfeited and expired, weighted-average exercise price	$ 30.77
Outstanding, end of year, weighted-average contractual life, Options	4.3
Outstanding, end of year, aggregate intrinsic value, options	$ 14,959
Vested or expected to vest, end of year, number of shares	1,341
Vested or expected to vest, end of year, weighted-average exercise price	$ 27.31
Vested or expected to vest, end of year, weighted-average contractual life	4.2
Vested or expected to vest, end of year, aggregate intrinsic value	13,275
Exercisable, end of year, number of shares	518
Exercisable, end of year, weighted-average exercise price	$ 26.16
Exercisable, end of year, weighted-average contractual life	2.3
Exercisable, end of year, aggregate intrinsic value	$ 5,721