Share-Based Compensation (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2011 Year Segments Derivative
Options outstanding and exercisable under the Company's 1991 Equity and Performance Incentive Plan
Outstanding, Shares, Beginning balance	3,152
Outstanding, Weighted average exercise price, Beginning balance	$ 36.67
Expired or forfeited, Shares	(226)
Expired or forfeited, Weighted average exercise price	$ 35.56
Exercised, Shares	(148)
Exercised, Weighted average exercise price	$ 27.06
Granted, Shares	436
Granted, Weighted average exercise price	$ 33.15
Outstanding, Shares, Ending balance	3,214
Outstanding, Weighted average exercise price, Ending balance	$ 36.68
Outstanding, Weighted Average Remaining Contractual Term	5
Outstanding, Aggregate Intrinsic Value	$ 1,430
Options exercisable, Shares	2,163
Options exercisable, Weighted average exercise price	$ 39.90
Option exercisable, Weighted average remaining contractual term	3
Option exercisable, aggregate Intrinsic Value	815
Options vested and expected to vest, Shares	3,189
Options vested and expected to vest, Weighted average exercise price	$ 36.74
Options vested and expected to vest, Weighted average remaining contractual term	5
Options vested and expected to vest, aggregate intrinsic value	$ 1,416