Comparison of Total Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Segment and Geographic Distribution of Operations [Line Items]
Assets	$ 1,792,270	$ 1,827,739
Investments in, at equity, and advances to unconsolidated companies	658	1,039
All Other Segments
Segment and Geographic Distribution of Operations [Line Items]
Assets	4,960	7,440
Operating Segments | Americas
Segment and Geographic Distribution of Operations [Line Items]
Assets	375,087	380,168
Operating Segments | Middle East/Asia Pacific
Segment and Geographic Distribution of Operations [Line Items]
Assets	238,283	233,611
Operating Segments | Europe/Mediterranean Sea
Segment and Geographic Distribution of Operations [Line Items]
Assets	415,409	316,524
Operating Segments | West Africa
Segment and Geographic Distribution of Operations [Line Items]
Assets	400,876	483,234
Corporate
Segment and Geographic Distribution of Operations [Line Items]
Assets	$ 356,997	$ 405,723