Divestitures	12 Months Ended
Dec. 31, 2015
Acquisitions and divestitures [Abstract]
Divestitures	DIVESTITURES Oil and Natural Gas In August 2013, we sold additional Bakken property interests. The proceeds, net of related expenses, were $57.1 million. In addition, we had other non-core asset sales with proceeds, net of related expenses, of $21.7 million, $33.1 million, and $1.9 million in 2013, 2014, and 2015, respectively. Proceeds from these dispositions reduced the net book value of the full cost pool with no gain or loss recognized. Contract Drilling During 2013, we sold five 2,000-3,000 horsepower drilling rigs to unaffiliated third-parties for a gain of $16.5 million. Four of our idle drilling rigs were classified as assets held for sale at December 31, 2013. These four drilling rigs were sold to an unaffiliated third party in the first quarter of 2014. The proceeds of this sale, less costs to sell, exceeded the $16.3 million net book value of the drilling rigs, both in the aggregate and for each drilling rig, resulting in a gain of $9.6 million. During the first quarter of 2015, we sold one drilling rig to an unaffiliated third party for $0.3 million resulting in a gain of $7,900. During the third quarter, we sold 30 drilling rigs, some old top drive equipment, and drill pipe in an auction. The proceeds from the sale of those assets, less costs to sell, was less than the $11.0 million net book value resulting in a loss of $7.3 million pre-tax.

Divestitures

12 Months Ended

Dec. 31, 2015

Acquisitions and divestitures [Abstract]

DIVESTITURES

Oil and Natural Gas

In August 2013, we sold additional Bakken property interests. The proceeds, net of related expenses, were $57.1 million. In addition, we had other non-core asset sales with proceeds, net of related expenses, of $21.7 million, $33.1 million, and $1.9 million in 2013, 2014, and 2015, respectively. Proceeds from these dispositions reduced the net book value of the full cost pool with no gain or loss recognized.

Contract Drilling

During 2013, we sold five 2,000-3,000 horsepower drilling rigs to unaffiliated third-parties for a gain of $16.5 million. Four of our idle drilling rigs were classified as assets held for sale at December 31, 2013.

These four drilling rigs were sold to an unaffiliated third party in the first quarter of 2014. The proceeds of this sale, less costs to sell, exceeded the $16.3 million net book value of the drilling rigs, both in the aggregate and for each drilling rig, resulting in a gain of $9.6 million.

During the first quarter of 2015, we sold one drilling rig to an unaffiliated third party for $0.3 million resulting in a gain of $7,900. During the third quarter, we sold 30 drilling rigs, some old top drive equipment, and drill pipe in an auction. The proceeds from the sale of those assets, less costs to sell, was less than the $11.0 million net book value resulting in a loss of $7.3 million pre-tax.