Taxes - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Valuation Allowance [Line Items]
Operating loss carryforwards	$ 178,700,000			$ 178,700,000	$ 167,000,000
Capital losses before valuation allowance	228,100,000			228,100,000	232,200,000
Net operating loss carryforward from foreign subsidiaries	355,900,000			355,900,000	356,100,000
Increase in valuation allowance				37,700,000
Unrecognized tax benefits	2,200,000			2,200,000	3,300,000	$ 2,900,000	$ 5,900,000
Unrecognized income tax penalties and interest accrued	1,400,000			1,400,000	2,000,000
Unrecognized tax benefit included in income tax expense (recovery)				$ (600,000)	400,000	(2,100,000)
Equity tax rates		0.40%	1.00%	1.15%
Equity tax				$ 3,769,000	0	$ 0
Equity taxes payable	$ 0			0	$ 0
Colombia [Member]
Valuation Allowance [Line Items]
Increase in deferred tax liability				$ 31,000,000
Colombia [Member] | Tax Year 2015 [Member]
Valuation Allowance [Line Items]
CREE surtax rate	5.00%
Consolidated income tax rate, CREE tax and surtax, combined (percent)	39.00%
Colombia [Member] | Tax Year 2016 [Member]
Valuation Allowance [Line Items]
CREE surtax rate	6.00%
Consolidated income tax rate, CREE tax and surtax, combined (percent)	40.00%
Colombia [Member] | Tax Year 2017 [Member]
Valuation Allowance [Line Items]
CREE surtax rate	8.00%
Consolidated income tax rate, CREE tax and surtax, combined (percent)	42.00%
Colombia [Member] | Tax Year 2018 [Member]
Valuation Allowance [Line Items]
CREE surtax rate	9.00%
Consolidated income tax rate, CREE tax and surtax, combined (percent)	43.00%
Colombia [Member] | Tax Year 2019 and Thereafter [Member]
Valuation Allowance [Line Items]
Foreign income tax rate	34.00%