Acquisitions (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Aug. 22, 2014	Dec. 21, 2013	Jun. 30, 2014
Business Acquisition [Line Items]
Goodwill	$ 72,212				$ 69,837
Net purchase price	5,551	51,398
HDB, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Name of Acquired Entity			HDB Ltd. Limited Partnership ("HDB").
Current assets			1,658
Property, plant and equipment			1,001
Other intangible assets			900
Total assets acquired			6,613
Current liabilities			1,062
Net assets acquired			5,551
Business Acquisition, Goodwill, Expected Tax Deductible Amount			3,054
Business Combination, Consideration Transferred			5,551
Kvaerner NAC
Business Acquisition [Line Items]
Business Acquisition, Name of Acquired Entity				Kvaerner North American Construction Ltd. and substantially all of the assets of Kvaerner North American Construction Inc
Current assets				83,575
Property, plant and equipment				11,377
Goodwill				39,295
Other intangible assets				24,009
Total assets acquired				158,256
Current liabilities				68,115
Deferred income taxes				1,179
Noncontrolling interest of consolidated joint venture	7,600			700
Net assets acquired				88,262
Cash acquired				36,655
Net purchase price				51,607
Business Acquisition, Goodwill, Expected Tax Deductible Amount				28,500
Business Combination, Consideration Transferred				$ 88,300