Detail of Certain Balance Sheet Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Activity in allowance for doubtful accounts
Balance at beginning of year	$ 5,158	$ 4,379	$ 4,460
Bad debt expense (benefit)	(27)	1,552	1,275
Deductions for uncollectible receivables written off, net of recoveries	(876)	(798)	(1,650)
Allowance for doubtful accounts of acquired companies at date of acquisition	33	25	294
Balance at end of year	4,288	5,158	$ 4,379
Other current liabilities
Accrued warranty costs	6,702	7,746
Accrued job losses	1,269	1,365
Accrued sales and use tax	1,973	2,216
Deferred revenue	5,257	2,175
Liabilities due to former owners	4,196	2,650
Other current liabilities	14,864	12,525
Total other current liabilities	$ 34,261	$ 28,677