Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer before post-closing adjustment and transaction fees.

No definition available.

Acquisitions (Details) $ / shares in Units, $ in Thousands								1 Months Ended	12 Months Ended
Acquisitions (Details) $ / shares in Units, $ in Thousands	Oct. 20, 2017 USD ($)	Sep. 13, 2017 USD ($) Branch State $ / shares shares	Jul. 10, 2017 USD ($) Vessel bbl hp	Oct. 11, 2016 USD ($) State	Jun. 30, 2016 USD ($) Vessel bbl	Jun. 02, 2016 USD ($) Vessel	Apr. 15, 2016 USD ($) Vessel bbl	Jul. 31, 2017 USD ($) Vessel	Dec. 31, 2017 USD ($)	Jun. 26, 2017 USD ($)	Jun. 25, 2017 USD ($)	Dec. 31, 2016 USD ($)
Assets [Abstract]
Goodwill									$ 935,135			$ 598,131
Sneed Shipbuilding, Inc [Member]
Total consideration transferred [Abstract]
Cash consideration paid	$ 14,852
Stewart & Stevenson LLC [Member]
Business Acquisition [Line Items]
Purchase price before post-closing adjustment and transaction fees		$ 758,245
Assumption of debt		$ 13,724
Issuance of shares (in shares) \| shares		5,696,259
Price per share (in dollars per share) \| $ / shares		$ 64.35
Term debt assumed		$ 12,135
Number of branches \| Branch		42
Number of states having branches \| State		12
Intangible assets acquired		$ 155,722
Weighted average amortization period of intangibles									16 years 9 months 18 days
Acquisition related costs		21,190
Total consideration transferred [Abstract]
Cash consideration paid		377,967
Stock consideration through issuance of Company common stock		366,554
Fair value of consideration transferred		744,521
Assets [Abstract]
Cash		98
Accounts receivable		97,891
Inventories		150,000
Prepaid expenses and other current assets		3,850
Property and equipment		141,885
Goodwill		331,728
Other assets		158,130
Total assets		883,582
Liabilities [Abstract]
Current portion of long-term debt		1,501
Bank notes payable		1,589
Income taxes payable		850
Accounts payable		72,200
Accrued liabilities		31,803
Deferred revenues		18,806
Long-term debt		10,634
Other long-term liabilities		1,678
Total liabilities		139,061
Net assets acquired		$ 744,521
Stewart & Stevenson LLC [Member] \| Revolving Credit Facility [Member]
Business Acquisition [Line Items]
Maximum borrowing capacity										$ 850,000	$ 550,000
Maturity date									Jun. 26, 2022
Undisclosed Competitor [Member]
Business Acquisition [Line Items]
Intangible assets acquired			$ 30
Weighted average amortization period of intangibles									2 years
Total consideration transferred [Abstract]
Cash consideration paid			68,000
Assets [Abstract]
Property and equipment			$ 67,970
Undisclosed Competitor [Member] \| Pressure Tank Barges [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired \| Vessel			9
Undisclosed Competitor [Member] \| Barrel Tank Barges [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired \| Vessel			4
Tank barge barrel capacity \| bbl			30,000
Undisclosed Competitor [Member] \| Inland Tank Barges [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired \| Vessel			13
Average age of property									5 years
Undisclosed Competitor [Member] \| Inland Towboats [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired \| Vessel			3
Horsepower of inland towboats \| hp			1,320
Valley Power Systems Northwest, Inc. [Member]
Business Acquisition [Line Items]
Intangible assets acquired				$ 2,070
Weighted average amortization period of intangibles									15 years
Number of western states included in distributor agreement \| State				9
Total consideration transferred [Abstract]
Fair value of consideration transferred				$ 11,440
Assets [Abstract]
Goodwill				$ 8,330
Barge Fleeting and Marine Fueling Operation Business [Member]
Total consideration transferred [Abstract]
Fair value of consideration transferred								$ 3,900
Barge Fleeting and Marine Fueling Operation Business [Member] \| Inland Tank Barges [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired \| Vessel								4
Total consideration transferred [Abstract]
Fair value of consideration transferred								$ 1,450
TD Equipment Finance, Inc. [Member]
Total consideration transferred [Abstract]
Cash consideration paid					$ 13,682
TD Equipment Finance, Inc. [Member] \| Coastal Tank Barge [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired \| Vessel					1
Tank barge barrel capacity \| bbl					80,000
Crosby Marine Transportation LLC [Member]
Total consideration transferred [Abstract]
Cash consideration paid						$ 26,450
Crosby Marine Transportation LLC [Member] \| Coastal Tugboats [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired \| Vessel						4
Average age of property									13 years
SEACOR Holdings Inc. [Member]
Business Acquisition [Line Items]
Ownership transferred, value							$ 3,681
Intangible assets acquired							0
Total consideration transferred [Abstract]
Cash consideration paid							85,500
Fair value of consideration transferred							89,181
Assets [Abstract]
Goodwill							$ 985
SEACOR Holdings Inc. [Member] \| Inland Tank Barges [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired \| Vessel							27
Tank barge barrel capacity \| bbl							30,000
Average age of property									10 years
SEACOR Holdings Inc. [Member] \| Inland Towboats [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired \| Vessel							14