6. Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings per share:
Weighted average common shares - basic	22,473	23,894	23,019	24,574
Incremental common shares attibutable to exercise of outstanding options and warrants	4,306	4,609	4,587	4,679
Weighted average number of common shares used to compute diluted earnings per share	26,779	28,503	27,606	29,253