Business Combinations - 2017 Combinations (Details) - USD ($) $ in Thousands	Jun. 16, 2017	May 30, 2017	May 26, 2017	Jun. 30, 2017	Dec. 31, 2016
Business combinations
Cash payment made		$ 2,300
Fixed assets		200
Intangibles assets		$ 2,100
Goodwill				$ 150,672	$ 127,226
FGC
Business combinations
Cash payment made			$ 33,000
Potential contingent consideration			$ 1,500
Contingent earnout period (in years)			1 year
Fair value of the contingent consideration			$ 1,200
Fixed assets			4,800
Working capital			4,200
Intangibles assets			10,500
Goodwill			14,700
Land and buildings			$ 3,500
The period of time goodwill and/or other intangible assets are deductible for income tax purposes			15 years
Coastal
Business combinations
Cash payment made	$ 27,500
Fixed assets	4,000
Working capital	4,800
Intangibles assets	9,900
Goodwill	$ 8,800
The period of time goodwill and/or other intangible assets are deductible for income tax purposes	15 years