Income Taxes - Summary of Net Operating Loss Carryforwards (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Deferred tax assets, operating loss, and other carryforwards
Net operating loss (NOL) carryforwards	$ 120,457
Total NOL and Other Carryforwards	151,618
Canada province
Deferred tax assets, operating loss, and other carryforwards
Net operating loss (NOL) carryforwards	46,424
Other foreign
Deferred tax assets, operating loss, and other carryforwards
Net operating loss (NOL) carryforwards	14,451
U.S. states
Deferred tax assets, operating loss, and other carryforwards
Net operating loss (NOL) carryforwards	10,960
Canada
Deferred tax assets, operating loss, and other carryforwards
Net operating loss (NOL) carryforwards	48,622
Other Carryforwards
Deferred tax assets, operating loss, and other carryforwards
Other deductible carryforwards	31,161
Other Carryforwards | Canada province
Deferred tax assets, operating loss, and other carryforwards
Other deductible carryforwards	22,033
Other Carryforwards | Other foreign
Deferred tax assets, operating loss, and other carryforwards
Other deductible carryforwards	$ 1,226
Other Carryforwards, expiration date	2018
Other Carryforwards | Canada
Deferred tax assets, operating loss, and other carryforwards
Other deductible carryforwards	$ 7,902
Earliest period | Canada province
Deferred tax assets, operating loss, and other carryforwards
Operating loss carryforward expiration	2024
Earliest period | U.S. states
Deferred tax assets, operating loss, and other carryforwards
Operating loss carryforward expiration	2019
Earliest period | Canada
Deferred tax assets, operating loss, and other carryforwards
Operating loss carryforward expiration	2024
Latest period | Canada province
Deferred tax assets, operating loss, and other carryforwards
Operating loss carryforward expiration	2037
Latest period | U.S. states
Deferred tax assets, operating loss, and other carryforwards
Operating loss carryforward expiration	2028
Latest period | Canada
Deferred tax assets, operating loss, and other carryforwards
Operating loss carryforward expiration	2037