Background of companies included in consolidation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Background of companies included in consolidation [Line Items]
Assets	$ 4,684,151	$ 4,268,094	$ 4,296,236
Liabilities	(2,549,679)	(2,130,292)	(2,048,768)
Equity	2,134,472	2,137,802	$ 2,247,468	$ 2,307,272
Parent [Member]
Background of companies included in consolidation [Line Items]
Assets	4,069,649	3,737,892
Liabilities	(1,983,382)	(1,652,401)
Equity	$ 2,086,267	$ 2,085,491

Expiry date 2020-01-01: The amount of resources: (a) controlled by the entity as a result of past events; and (b) from which future economic benefits are expected to flow to the entity. Effective 2020-01-01: The amount of a present economic resource controlled by the entity as a result of past events. Economic resource is a right that has the potential to produce economic benefits.

The amount of residual interest in the assets of the entity after deducting all its liabilities.

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- Definition

Expiry date 2020-01-01: The amount of present obligations of the entity arising from past events, the settlement of which is expected to result in an outflow from the entity of resources embodying economic benefits. Effective 2020-01-01: The amount of a present obligation of the entity to transfer an economic resource as a result of past events. Economic resource is a right that has the potential to produce economic benefits.

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