Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2013	6,901
Balance at Dec. 31, 2013	$ 69,000	$ 20,291,000	$ 65,230,000		$ 85,590,000
Share-based compensation (in shares)	20
Share-based compensation	$ 1,000	1,118,000			1,119,000
Exercise of stock options net of shares presented for exercise (in shares)	148
Exercise of stock options net of shares presented for exercise	$ 1,000	335,000			336,000
Net share settlement of restricted stock units and stock option tax w/h		(831,000)			(831,000)
Excess tax benefits on share-based compensation		1,219,000			1,219,000
Net income from consolidated operations			7,559,000		7,559,000
Balance (in shares) at Dec. 31, 2014	7,069
Balance at Dec. 31, 2014	$ 71,000	22,132,000	72,789,000		94,992,000
Share-based compensation (in shares)	24
Share-based compensation		1,069,000			1,069,000
Exercise of stock options net of shares presented for exercise (in shares)	77
Exercise of stock options net of shares presented for exercise	$ 1,000	357,000			358,000
Net share settlement of restricted stock units and stock option tax w/h		(209,000)			(209,000)
Excess tax benefits on share-based compensation		356,000			356,000
Net income from consolidated operations			7,593,000		7,593,000
Balance (in shares) at Dec. 31, 2015	7,140			30
Balance at Dec. 31, 2015	$ 72,000	23,705,000	80,382,000	$ (587,000)	103,572,000
Repurchase of common stock (in shares)	(30)			30
Repurchase of common stock				$ (587,000)	(587,000)
Share-based compensation (in shares)	33
Share-based compensation		1,056,000			1,056,000
Exercise of stock options net of shares presented for exercise (in shares)	48
Exercise of stock options net of shares presented for exercise		529,000			529,000
Net share settlement of restricted stock units and stock option tax w/h		(219,000)			(219,000)
Excess tax benefits on share-based compensation		145,000			145,000
Net income from consolidated operations			7,970,000		7,970,000
Balance (in shares) at Dec. 31, 2016	7,212			30
Balance at Dec. 31, 2016	$ 72,000	$ 25,216,000	$ 88,352,000	$ (587,000)	$ 113,053,000