Shareholders' Equity and Common Stock Equivalents (Details 1) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary of changes in outstanding options
Weighted Average Option Price per Share, Beginning Balance	$ 21.22
Weighted Average Option Price per Share, Options Granted	32.44
Weighted Average Option Price per Share, Options Vested	21.23
Weighted Average Option Price per Share, Options Exercised	17.71
Weighted Average Option Price per Share, Options Forfeited	23.10
Weighted Average Option Price per Share, Options Expired	0
Weighted Average Option Price per Share, Ending Balance	24.00	$ 21.22
Range of Option Prices per Share, Expired	$ 0
Options Outstanding, Beginning Balance	634,437	956,814
Options Outstanding, Granted	142,908	175,632	245,424
Options Outstanding, Vested	0
Options Outstanding, Exercised	85,532	435,665	1,158,537
Options Outstanding, Forfeited	(22,120)
Options Outstanding, Expired	0
Options Outstanding, Ending Balance	669,693	634,437	956,814
Options Vested and Exercisable, Beginning Balance	208,578
Options Vested and Exercisable, Granted	0
Options Vested and Exercisable, Vested	158,586
Options Vested and Exercisable, Exercisable	(85,532)
Options Vested and Exercisable, Forfeited	0
Options Vested and Exercisable, Expired	0
Options Vested and Exercisable, Ending Balance	281,632	208,578
Minimum [Member]
Summary of changes in outstanding options
Range of Option Prices per Share, Beginning Balance	$ 6.91
Range of Option Prices per Share, Granted	32.35
Range of Option Prices per Share, Vested	13.83
Range of Option Prices per Share, Exercised	13.83
Range of Option Prices per Share, Forfeited	17.01
Range of Option Prices per Share, Ending Balance	6.91	$ 6.91
Maximum [Member]
Summary of changes in outstanding options
Range of Option Prices per Share, Beginning Balance	30.24
Range of Option Prices per Share, Granted	33.41
Range of Option Prices per Share, Vested	30.24
Range of Option Prices per Share, Exercised	28.88
Range of Option Prices per Share, Forfeited	28.88
Range of Option Prices per Share, Ending Balance	$ 33.41	$ 30.24