CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Trade accounts receivable, allowances for doubtful accounts	$ 10,761	$ 8,798	$ 10,761	$ 8,798
Accumulated amortization	$ 53,688	$ 44,410	$ 53,688	$ 44,410
Shareholders' equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000	100,000,000	100,000,000
Common stock shares issued (in shares)	14,444,511	14,468,485	14,444,511	14,468,485
Treasury stock (in shares)	214,724	146,871	214,724	146,871
Series A Preferred Stock [Member]
Shareholders' equity:
Preferred stock, voting rights	1/10th vote per share	1/10th vote per share
Preferred stock, par value (in dollars per share)			$ 1.00	$ 1.00
Preferred stock, liquidation preference (in dollars per share)			$ 112	$ 100
Preferred stock, authorized (in shares)			1,000,000	1,000,000
Preferred stock, issued (in shares)			1,122	1,122
Preferred stock, outstanding (in shares)			1,122	1,122
Series B Convertible Preferred Stock [Member]
Shareholders' equity:
Preferred stock, voting rights	1/10th vote per share	1/10th vote per share
Preferred stock, par value (in dollars per share)			$ 1.00	$ 1.00
Preferred stock, stated value (in dollars per share)			$ 100	$ 100
Preferred stock, liquidation preference (in dollars per share)			$ 1,500	$ 100
Preferred stock, authorized (in shares)			1,000,000	1,000,000
Preferred stock, issued (in shares)			15,000	15,000
Preferred stock, outstanding (in shares)			15,000	15,000