Employee Benefits (Details) - USD ($) $ in Thousands  | 
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016  | 
Dec. 31, 2015  | 
Dec. 31, 2014  | 
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| 401(k) | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Employer matching contribution percent | 100.00% | ||
| Employer matching percent | 6.00% | ||
| Employer contributions | $ 4,600 | $ 4,733 | $ 4,556 | 
| GPPP | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Employer matching contribution percent | 100.00% | ||
| Employer matching percent | 6.00% | ||
| Employer contributions | $ 202 | ||
| RRSP | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Employer matching contribution percent | 100.00% | ||
| Employer matching percent | 6.00% | ||
| Employer contributions | $ 307 | $ 411 | $ 475 | 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition The amount of the cost recognized during the period for defined contribution plans. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. No definition available. 
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- Definition Percentage employer matches of the employee's percentage contribution matched. No definition available. 
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