Deferred tax reconciliation (Details 5) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Change in net deferred income tax liability from the preceding table	$ 9,515
Deferred taxes associated with other comprehensive loss	1,817
Excess deferred income tax amortization	(12,517)
Other	(616)
Deferred income taxes	$ (1,801)	$ 63,415	$ 59,735