Commitments and Contingent Liabilities - Additional Information (Detail) SEK in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Bonds	Dec. 31, 2016 SEK
Commitments and Contingent Liabilities [Line Items]
Outstanding standby and commercial letters of credit | $	$ 22,305
Percentage on employees covered by collective bargaining agreements	38.00%	38.00%
Bargaining agreement beginning expiration year	2017-09
Bargaining agreement ending expiration year	2020-02
Akers AB [Member]
Commitments and Contingent Liabilities [Line Items]
Number of surety bonds issued | Bonds	2
Amount covered by guarantees	$ 4,000	SEK 33,900
Collective Bargaining Agreement Two [Member]
Commitments and Contingent Liabilities [Line Items]
Percentage of covered employees	28.00%