Segment Reporting - Information about Segment Assets by Country (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total assets	$ 3,138,372	$ 3,387,076
Operating Segments [Member] | AEA [Member]
Segment Reporting Information [Line Items]
Total assets	731,872	896,822
Operating Segments [Member] | MEA [Member]
Segment Reporting Information [Line Items]
Total assets	973,018	971,170
Operating Segments [Member] | ASA [Member]
Segment Reporting Information [Line Items]
Total assets	853,771	774,365
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total assets	$ 579,711	$ 744,719