Share-Based Compensation and Equity - Stock Option Activity (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Options outstanding and exercisable under the Company's 1991 Equity and Performance Incentive Plan
Outstanding, Shares, Beginning balance	3,201
Outstanding, Weighted average exercise price, Beginning balance	$ 36.70
Expired or forfeited, Shares	(555)
Expired or forfeited, Weighted average exercise price	$ 37.33
Exercised, Shares	(554)
Shares exercised, Weighted average exercise price	$ 30.11
Granted, Shares	576
Granted, Weighted average exercise price	$ 34.98
Outstanding, Shares, Ending balance	2,668		3,201
Outstanding, Weighted average exercise price, Ending balance	$ 37.56		$ 36.70
Outstanding, Weighted Average Remaining Contractual Term	5 years
Outstanding, Aggregate Intrinsic Value	$ 2,617	[1]
Options exercisable, Shares	1,572
Options exercisable, Weighted average exercise price	$ 40.96
Option exercisable, Weighted average remaining contractual term	3 years
Option exercisable, aggregate Intrinsic Value	1,703	[1]
Options vested and expected to vest, Shares	2,638	[2]
Options vested and expected to vest, Weighted average exercise price	$ 37.62	[2]
Options vested and expected to vest, Weighted average remaining contractual term	5 years
Options vested and expected to vest, aggregate intrinsic value	2,589	[1],[2]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	4,393		936	510
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 10.43		$ 10.90	$ 9.46
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	3,413		2,967	3,059
Proceeds from Stock Options Exercised	16,679		4,043	3,332
Income tax benefit (detriment) from share-based compensation	(982)		(1,362)	1,705
Stock Options [Member]
Options outstanding and exercisable under the Company's 1991 Equity and Performance Incentive Plan
Income tax benefit (detriment) from share-based compensation	$ (982)		$ (1,362)	$ 1,705

[1] The aggregate intrinsic value represents the total pre-tax intrinsic value (the difference between the Company’s closing share price on the last trading day of the year in 2012 and the exercise price, multiplied by the number of “in-the-money” options) that would have been received by the option holders had all option holders exercised their options on December 31, 2012. The amount of aggregate intrinsic value will change based on the fair market value of the Company’s common shares.

[2] The expected to vest options are the result of applying the pre-vesting forfeiture rate assumption to total outstanding non-vested options.