Shareholders' Equity and Stock Options (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of changes in outstanding options
Weighted Average Option Price per Share, Beginning Balance	$ 14.73
Weighted Average Option Price per Share, Options Granted	$ 20.97
Weighted Average Option Price per Share, Options Vested	$ 13.94
Weighted Average Option Price per Share, Options Exercised	$ 13.77
Weighted Average Option Price per Share, Options Forfeited	$ 17.02
Weighted Average Option Price per Share, Options Expired	$ 18.17
Range of Option Prices per Share, Beginning Balance	$ 17.49
Range of Option Prices per Share, Expired	$ 18.17
Range of Option Prices per Share, Ending Balance		$ 17.49
Options outstanding, Beginning Balance	1,882,939	2,600,583
Outstanding Options, Granted	245,424	296,188	313,000
Outstanding Options, Vested	0
Outstanding Options, Exercised	(1,158,537)	(389,089)	(136,290)
Outstanding Options, Forfeited	(3,962)
Outstanding Options, Expired	(9,050)
Options outstanding, Ending Balance	956,814	1,882,939	2,600,583
Vested and Exercisable, Beginning Balance	1,161,703
Vested and Exercisable, Granted	0
Vested and Exercisable, Vested	324,291
Vested and Exercisable, Exercisable	(1,158,537)
Vested and Exercisable, Forfeited	(3,962)
Vested and Exercisable, Expired	(9,050)
Vested and Exercisable, Ending Balance	314,445	1,161,703
Maximum [Member]
Summary of changes in outstanding options
Weighted Average Option Price per Share, Options Granted	$ 30.24
Range of Option Prices per Share, Beginning Balance	$ 20.23
Range of Option Prices per Share, Granted	$ 30.24
Range of Option Prices per Share, Vested	$ 20.60
Range of Option Prices per Share, Exercised	$ 20.23
Range of Option Prices per Share, Forfeited	$ 20.60
Range of Option Prices per Share, Ending Balance	$ 30.24
Minimum [Member]
Summary of changes in outstanding options
Weighted Average Option Price per Share, Options Granted	$ 20.60
Range of Option Prices per Share, Beginning Balance	$ 6.91
Range of Option Prices per Share, Granted	$ 20.60
Range of Option Prices per Share, Vested	$ 6.91
Range of Option Prices per Share, Exercised	$ 6.91
Range of Option Prices per Share, Forfeited	$ 13.83
Range of Option Prices per Share, Ending Balance	$ 6.91