Stock Based Compensation (Details) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
1/16/2013 [Member] | 2005 Employee Stock Plan [Member]
Restricted stock compensation footnote
Shares Granted		2,000
Fair Value		$ 30.48
Vesting Period	Ratably over 3 years from grant date
2/14/2013 [Member] | 2005 Employee Stock Plan [Member]
Restricted stock compensation footnote
Shares Granted		93,800
Fair Value		$ 31.51
Vesting Period	Ratably over 5 years from grant date
5/21/2013 [Member] | 2010 Non-Employee Director Stock Plan [Member]
Restricted stock compensation footnote
Shares Granted		14,700
Fair Value		$ 33.17
Vesting Period	At the end of 5 years from grant date