Stock-Based Compensation (details) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]
Additional Ltip Shares Authorized	250,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	850,000	600,000
Common stock was authorized for grants under the LTIP	35,340
Weighted-average per share grant date fair value of unvested shares	$ 53.92
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Fair value pricing model LTIP	Monte-Carlo option pricing model
Stock price on valuation date	$ 48.00
Performance term (in years)	3.0
Quarterly Dividends Paid Per Share	$ 0.445
Expected dividend yield	3.60%
Dividend Discount Factor	0.9012
Stock Issued or Granted During Period, Share-based Compensation [Abstract]
Stock Price On Restricted Stock Unit Grant Date, Maximum	$ 48.25
Shares granted under RSU	22,220
Stock Price On Restricted Stock Unit Grant Date, Minimum	$ 48.00
Unrecognized compensation cost	$ 600,000
Unrecognized compensation cost, period for recognition	through 2014