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Employee Benefit Plans - Additional Information (Narrative) (Details)
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12 Months Ended | ||||||||
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Dec. 31, 2014
401(k) Profit Sharing Plan
USD ($)
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Dec. 31, 2013
401(k) Profit Sharing Plan
USD ($)
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Dec. 31, 2012
401(k) Profit Sharing Plan
USD ($)
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Dec. 31, 2014
Group Registered Retirement Savings Plan
Canadian Air Crane Ltd
USD ($)
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Dec. 31, 2014
Group Registered Retirement Savings Plan
Canadian Air Crane Ltd
CAD
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Dec. 31, 2013
Group Registered Retirement Savings Plan
Canadian Air Crane Ltd
USD ($)
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Dec. 31, 2013
Group Registered Retirement Savings Plan
Canadian Air Crane Ltd
CAD
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Dec. 31, 2012
Group Registered Retirement Savings Plan
Canadian Air Crane Ltd
USD ($)
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Dec. 31, 2012
Group Registered Retirement Savings Plan
Canadian Air Crane Ltd
CAD
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| Defined Benefit Plan Disclosure [Line Items] | |||||||||
| Defined Contribution Plan Maximum Deferred Compensation By Employees Percentage | 100.00% | 18.00% | 18.00% | ||||||
| Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent | 2.50% | 2.50% | 2.50% | 2.50% | 2.50% | 2.50% | |||
| Defined Contribution Plan Deferred Compensation By Employees Amount | $ 17,500 | $ 17,500 | $ 17,000 | ||||||
| Defined Contribution Plan, Cost Recognized | $ 1,000,000 | $ 300,000 | $ 400,000 | $ 100,000 | 24,270 | $ 100,000 | 23,820 | $ 100,000 | 22,970 |