Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2014

Quarterly Financial Data - Unaudited [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]

	Quarter Ended
	March 31		June 30		Sept. 30		Dec. 31
2014
Total revenue	$	73,230	$	78,677	$	77,457	$	79,896
Gross profit	$	36,027	$	37,542	$	38,147	$	39,685
Net income	$	6,657	$	5,878	$	6,428	$	7,372
Net income per share:
Basic	$	0.44	$	0.39	$	0.42	$	0.48
Diluted	$	0.43	$	0.38	$	0.42	$	0.46
2013
Total revenue	$	74,299	$	78,661	$	82,815	$	77,941
Gross profit	$	36,794	$	38,038	$	40,955	$	38,945
Net income	$	8,685	$	7,367	$	11,034	$	13,332
Net income per share:
Basic	$	0.60	$	0.50	$	0.75	$	0.89
Diluted	$	0.58	$	0.48	$	0.72	$	0.86