Goodwill by Operating Segment (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Goodwill [Line Items]
Balance at beginning of period	$ 611,473
Goodwill acquired	0
Balance at end of period	611,473
Contract Drilling
Goodwill [Line Items]
Balance at beginning of period	395,060
Goodwill acquired	0
Balance at end of period	395,060
Pressure Pumping
Goodwill [Line Items]
Balance at beginning of period	121,444
Goodwill acquired	0
Balance at end of period	121,444
Directional Drilling
Goodwill [Line Items]
Balance at beginning of period	88,685
Goodwill acquired	0
Balance at end of period	88,685
Oilfield Rentals
Goodwill [Line Items]
Balance at beginning of period	6,284
Goodwill acquired	0
Balance at end of period	$ 6,284