Business Segments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Disclosure [Line Items]
Number of reportable business segments	3
Long-lived assets	$ 3,615,383	$ 3,167,266
United States
Segment Reporting Disclosure [Line Items]
Marketable land-based drilling rigs	314
Alaska
Segment Reporting Disclosure [Line Items]
Marketable land-based drilling rigs	314
Western and Northern Canada
Segment Reporting Disclosure [Line Items]
Marketable land-based drilling rigs	314
Canada | Contract Drilling
Segment Reporting Disclosure [Line Items]
Oil and gas services	79,400	106,000	65,700
Long-lived assets	$ 72,600	$ 69,800