Acquisitions (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Aug. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Aug. 01, 2016
Acquisition
Purchase price paid in cash			$ 109,065	$ 45,000	$ 109,065	$ 45,000
Vulcan
Acquisition
Business Acquisition, Percentage of Voting Interests Acquired							100.00%
Purchase price paid in cash	$ 113,000
Working capital purchased	29,200
Intangible assets	$ 32,930
Consolidated Systems, Inc [Member]
Acquisition
Purchase price paid in cash		$ 45,000
Working capital purchased		$ 30,000