Share-Based Compensation (Details 2) (Restricted Stock [Member], USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Restricted Stock [Member]
Summary of Nonvested Shares
Outstanding at January 1, 2012 , Shares	83,966
Outstanding at January 1, 2012, Weighted Average Grant Date Fair Value Per Share	$ 39.83
Granted, Shares	59,938		66,208
Granted, Weighted Average Grant Date Fair Value Per Share	$ 41.71		$ 37.76
Vested, Shares	(33,104)	[1]	(5,985)
Vested, Weighted Average Grant Date Fair Value Per Share	$ 37.76
Outstanding as of March 31, 2012, Shares	110,800
Outstanding as of March 31, 2012, Weighted Average Grant Date Fair Value Per Share	$ 41.46
Summary of Granted and Vested Shares
Granted, Shares	59,938		66,208
Granted, Weighted Average Grant Date Fair Value Per Share	$ 41.71		$ 37.76
Vested, Shares	(33,104)	[1]	(5,985)
Vested shares, total fair value	$ 1,274	[2]	$ 232	[2]

[1] The total shares vested include 22,312 shares that were tendered in accordance with the terms of the 2006 Plan to satisfy minimum statutory tax withholding requirements related to the restricted shares that have vested. We accept the return of shares at the current quoted closing share price of the Company's common stock to satisfy tax obligations

[2] Total fair value of shares vested was calculated based on the quoted closing share price of the Company's common stock on the NYSE on the day of vesting.