Segments and Geographic Area Analysis - Summary of Information about Disaggregated Revenue by Country (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Total revenues	$ 134,817	$ 229,170
Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	122,553	217,866
Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues	12,264	11,304
United States [Member]
Segment Reporting Information [Line Items]
Total revenues	80,039	108,044
United States [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	74,046	104,900
United States [Member] | Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues	5,993	3,144
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total revenues	26,041	35,844
United Kingdom [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	24,091	32,599
United Kingdom [Member] | Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues	1,950	3,245
Australia [Member]
Segment Reporting Information [Line Items]
Total revenues	14,827	22,103
Australia [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	11,673	17,188
Australia [Member] | Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues	3,154	4,915
Myanmar [Member]
Segment Reporting Information [Line Items]
Total revenues	10,489
Myanmar [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	9,322
Myanmar [Member] | Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues	1,167
Brazil [Member]
Segment Reporting Information [Line Items]
Total revenues	3,421	63,179
Brazil [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 3,421	$ 63,179