Comparison of Total Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Segment and Geographic Distribution of Operations [Line Items]
Assets	$ 1,809,298	$ 1,827,739
Investments in, at equity, and advances to unconsolidated companies	774	1,039
All Other Segments
Segment and Geographic Distribution of Operations [Line Items]
Assets	3,096	7,440
Operating Segments | Americas
Segment and Geographic Distribution of Operations [Line Items]
Assets	363,229	380,168
Operating Segments | Middle East/Asia Pacific
Segment and Geographic Distribution of Operations [Line Items]
Assets	241,576	233,611
Operating Segments | Europe/Mediterranean Sea
Segment and Geographic Distribution of Operations [Line Items]
Assets	413,330	316,524
Operating Segments | West Africa
Segment and Geographic Distribution of Operations [Line Items]
Assets	397,923	483,234
Corporate
Segment and Geographic Distribution of Operations [Line Items]
Assets	$ 389,370	$ 405,723