Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

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Fair value portion of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Non-cash impairment charges					$ 4,000
Aggregate carrying value of assets	$ 3,222,230					$ 3,222,820
Property plant and equipment, fair value					$ 14,000
Loss on disposal of assets				$ 3,000
Marine Assets [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Non-cash impairment charges		$ 12,000
Aggregate carrying value of assets		22,000
Estimated fair value of assets		$ 10,000
AEA [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Non-cash impairment charges			$ 32,000
AEA [Member] \| Marine Assets [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Non-cash impairment charges	$ 11,000
ASA [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Non-cash impairment charges				$ 7,000