Segment Reporting - Information about Segment Assets by Country (Detail) - USD ($) $ in Thousands		Jun. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total assets	[1]	$ 3,291,448	$ 3,222,230
Operating Segments [Member] | AEA [Member]
Segment Reporting Information [Line Items]
Total assets	[1]	626,524	727,328
Operating Segments [Member] | MEA [Member]
Segment Reporting Information [Line Items]
Total assets	[1]	1,530,971	907,936
Operating Segments [Member] | ASA [Member]
Segment Reporting Information [Line Items]
Total assets	[1]	750,650	976,470
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total assets	[1]	$ 383,303	$ 610,496

[1] Our marine vessels are included in the area in which they were located as of reporting date.