|
Income Taxes - Additional Information (Detail) (USD $)
|
3 Months Ended |
12 Months Ended |
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Jun. 30, 2013
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Dec. 31, 2012
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Jun. 30, 2012
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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| Operating Loss Carryforwards [Line Items] |
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|
|
|
|
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| Statutory federal income tax rate |
|
|
|
35.00% |
35.00% |
35.00% |
| North Dakota Corporate income tax rate |
|
|
|
4.53% |
5.15% |
|
| Reduction in deferred tax liability |
$ (1,100,000) |
|
|
|
|
|
| Adjustment to deferred tax asset and liabilities |
|
|
|
3,000,000 |
|
|
| Net operating loss carryforwards for federal income tax |
|
|
|
282,900,000 |
|
|
| Net operating loss carryforwards for state income tax |
|
|
|
158,400,000 |
|
|
| Deferred tax assets valuation allowance |
|
1,657,000 |
|
6,076,000 |
1,657,000 |
40,188,000 |
| Valuation allowance additions (release) |
|
(17,800,000) |
(20,700,000) |
|
|
|
| Unrecognized tax benefits |
|
|
|
283,000 |
|
|
| Unrecognized tax benefits, pertaining to accrued interest and penalties |
|
0 |
|
100,000 |
0 |
0 |
| Reduction in unrecognized tax benefit |
|
|
|
100,000 |
|
|
|
Discontinued Operations
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|
|
|
|
|
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| Operating Loss Carryforwards [Line Items] |
|
|
|
|
|
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| Unrecognized tax benefits |
|
0 |
|
|
0 |
0 |
| Unrecognized tax benefits that would impact effective tax rate if recognized |
|
|
|
300,000 |
|
|
|
State Net Operating Loss Carryforwards
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|
|
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
|
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| Deferred tax assets valuation allowance |
|
|
|
6,100,000 |
|
|
|
Valuation Allowance Release
|
|
|
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
|
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| Valuation allowance additions (release) |
|
|
|
|
$ (38,531,000) |
|
|
Minimum
|
|
|
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
|
|
| Net operating loss carryforwards for federal income tax, expiration year |
|
|
|
2030 |
|
|
| Net operating loss carryforwards for state income tax, expiration year |
|
|
|
2017 |
|
|
| Tax examination, statute of limitations |
|
|
|
3 years |
|
|
|
Maximum
|
|
|
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
|
|
| Net operating loss carryforwards for federal income tax, expiration year |
|
|
|
2033 |
|
|
| Net operating loss carryforwards for state income tax, expiration year |
|
|
|
2033 |
|
|
| Tax examination, statute of limitations |
|
|
|
4 years |
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