Acquisition (Details) $ in Thousands		3 Months Ended	12 Months Ended
	Feb. 17, 2015 USD ($)	Mar. 31, 2016 USD ($) acquisition	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Goodwill acquired during period		$ 3,000
Number of Acquisitions | acquisition		2
Ahmann and Martin Company
Business Acquisition [Line Items]
Common stock and cash issued in acquisition	$ 48,000
Maximum contingent consideration	$ 8,000
Goodwill acquired during period				$ 40,000
Other Intangibles
Business Acquisition [Line Items]
Additions to finite-lived intangible assets		$ 1,000	$ 1,012	$ 12,115	$ 0