Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Supplemental non-cash investing and financing activities:
Value of common stock issued in acquisitions	$ 0	$ 1,014
Exercise of stock options by common stock surrender	0	1,126
Supplemental cash payment information:
Interest paid	921	641
Income taxes paid, net of refunds	$ 3,429	$ 2,549