Equity (Details 3) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Remaining compensation expense to be recognized related to the future service period of unvested outstanding stock options
2014	$ 7,000		$ 7,000
2015	15,000		15,000
2016	15,000		15,000
2017	2,000		2,000
Employee Stock Option [Member]
Stock Based Compensation Plans
Number of shares exercised			11,666	22,000
Value of options exercised	277,000	523,000	277,000	523,000
Market value on the date of exercise	455,000	865,000	455,000	865,000
Options Granted			15,000
Exercise price (in dollars per share)			$ 38.43
Stock options granted (in shares)				0
Options outstanding at end of the period (in shares)	76,668		76,668
Options exercisable at end of the period (in shares)	61,668		61,668
Compensation expense related to the vesting of stock awards	4,000		5,000
Vesting period			3 years
Employee Stock Option [Member] | Vesting Through December312014 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	0		0
Employee Stock Option [Member] | Vesting Through December312015 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	5,000		5,000
Employee Stock Option [Member] | Vesting Through December312016 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	5,000		5,000
Employee Stock Option [Member] | Vesting Through December312017 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	5,000		5,000
Employee Stock Option [Member] | Vesting Beyond2017 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	0		0
Restricted Stock [Member]
Stock Based Compensation Plans
Compensation expense related to the vesting of stock awards	779,000	523,000	1,444,000	1,508,000
Options outstanding	240,381		240,381
Shares vested due to retirement of former SVP Marketing and Strategic Planning				18,180
Compensation expense related to the accelerated vesting				457,000
Remaining compensation expense to be recognized related to the future service period of unvested outstanding stock options
2014	1,745,000		1,745,000
2015	2,484,000		2,484,000
2016	1,262,000		1,262,000
2017	$ 190,000		$ 190,000
Restricted Stock [Member] | Vesting Through December312014 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	33,713		33,713
Restricted Stock [Member] | Vesting Through December312015 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	110,211		110,211
Restricted Stock [Member] | Vesting Through December312016 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	66,726		66,726
Restricted Stock [Member] | Vesting Through December312017 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	29,731		29,731
Restricted Stock [Member] | Vesting Beyond2017 [Member]
Stock Based Compensation Plans
Options scheduled to vest (in shares)	0		0
Restricted Stock [Member] | Grant Date Price36.26 [Member] | Vesting Date1 June2016 [Member]
Stock Based Compensation Plans
Granted (in shares)				20,000
Price per share				$ 36.26
Restricted Stock [Member] | Grant Date Price36.81 [Member]
Stock Based Compensation Plans
Granted (in shares)			59,000
Vesting period			3 years
Price per share			$ 36.81
Restricted Stock [Member] | Grant Date Price38.43 [Member]
Stock Based Compensation Plans
Granted (in shares)			3,000
Vesting period			3 years
Price per share			$ 38.43
Restricted Stock [Member] | Grant Date Price46.54 [Member]
Stock Based Compensation Plans
Granted (in shares)				8,400
Vesting period				3 years
Price per share				$ 46.54
Restricted Stock [Member] | Grant Date Price41.83 [Member]
Stock Based Compensation Plans
Granted (in shares)				6,000
Vesting period		3 years
Price per share				$ 41.83
Restricted Stock [Member] | Grant Date Price40.05[Member]
Stock Based Compensation Plans
Granted (in shares)	25,500
Price per share	$ 40.05
Restricted Stock [Member] | Grant Date Price40.05[Member] | Vesting Over Three Year Period From Grant Date [Member]
Stock Based Compensation Plans
Granted (in shares)	15,000
Vesting period	3 years
Restricted Stock [Member] | Grant Date Price40.05[Member] | Vesting ratably over one-year period from the grant date
Stock Based Compensation Plans
Granted (in shares)	10,500
Vesting period	1 year