Income Taxes (Income Tax Reconciliation) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%
Domestic statutory rate at 35%	$ 23,403,000	$ 21,212,000	$ 17,985,000
Increase (reduction) from:
Jurisdictional rate differences	(2,192,000)	(2,119,000)	(1,959,000)
Valuation allowance	797,000	353,000	(114,000)
Stock based compensation	257,000	199,000	136,000
U.S. state taxes	1,942,000	1,649,000	1,496,000
Domestic production deduction	(518,000)	(1,321,000)	(1,162,000)
R&D credit	(475,000)	(614,000)	(856,000)
Other, net	444,000	95,000	(232,000)
Total income taxes	$ 23,658,000	$ 19,454,000	$ 15,294,000
Effective tax rate	35.00%	32.00%	30.00%