Stock Based Compensation (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Mar. 09, 2012	Feb. 01, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value (in dollars per share)	$ 1				$ 1						$ 1
Number of key individuals	10				10
Share-based Compensation [Abstract]
Share-based Compensation Expense	$ 337,000		$ 398,000		$ 881,000		$ 1,404,000
Related Reduction in Earnings Per Share (in dollars per share)	$ (0.05)	[1]	$ (0.06)	[1]	$ (0.12)	[1]	$ (0.2)	[1]
Number of shares of common stock retired to meet tax liabilities (in shares)									16,439	13,665
Stock Awards [Member]
Share-based Compensation Expense [Abstract]
Allocated share-based compensation expense	30,000				390,000
Reduction of basic and diluted earnings per share due to stock-based compensation charges (in dollars per share)					$ 0.06
Shares [Roll Forward]
Non-vested - Beginning of Period (in shares)					87,500
Unrestricted Shares Granted (in shares)					5,712
Shares Vested (in shares)					(93,212)
Non-vested - End of Period (in shares)	0				0
Weighted Average Fair Value Per Share [Roll Forward]
Non-vested - Beginning of Period (in dollars per share)					$ 22.91
Restricted/Unrestricted Shares Granted (in dollars per share)					$ 21.01
Shares Vested (in dollars per share)					$ 22.79
Non-vested - End of Period (in dollars per share)	$ 0				$ 0
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value (in dollars per share)	$ 1				$ 1
Shares available for grant on attainment of performance targets (in shares)	81,875				81,875
Share-based Compensation Expense [Abstract]
Allocated share-based compensation expense	$ 307,000				$ 491,000
Reduction of basic and diluted earnings per share due to stock-based compensation charges (in dollars per share)	$ 0.04				$ 0.07
Shares [Roll Forward]
Non-vested - Beginning of Period (in shares)					0
Unrestricted Shares Granted (in shares)					65,500
Shares Vested (in shares)					0
Non-vested - End of Period (in shares)	65,500				65,500
Weighted Average Fair Value Per Share [Roll Forward]
Non-vested - Beginning of Period (in dollars per share)					$ 0
Restricted/Unrestricted Shares Granted (in dollars per share)					$ 21.48
Shares Vested (in dollars per share)					$ 0
Non-vested - End of Period (in dollars per share)	$ 21.48				$ 21.48
Number of top executives	2				2
Time Based Restricted Stock Units [Member]
Weighted Average Fair Value Per Share [Roll Forward]
Maximum shares allocated to each share based compensation unit	1				1
Vesting period					3 years
Absolute Performance Based Restricted Stock Units [Member]
Weighted Average Fair Value Per Share [Roll Forward]
Maximum shares allocated to each share based compensation unit	1.5				1.5
Vesting period					3 years
Absolute Performance Based Restricted Stock Units [Member] | Executive Officer [Member]
Weighted Average Fair Value Per Share [Roll Forward]
Vesting period					1 year
Relative Performance Based Restricted Stock Units [Member]
Weighted Average Fair Value Per Share [Roll Forward]
Maximum shares allocated to each share based compensation unit	1.5				1.5
Vesting period					3 years
Relative Performance Based Restricted Stock Units [Member] | Executive Officer [Member]
Weighted Average Fair Value Per Share [Roll Forward]
Vesting period					1 year

[1] Same for basic and diluted earnings per share