Intangible assets (Tables)

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets

		Cost		Accumulated Amortization		Net Book Value
Favorable lease terms December 31, 2017	$	83,716		(75,636)		8,080
Additions		—		(3,748)		(3,748)
Favorable lease terms December 31, 2018	$	83,716	$	(79,384)	$	4,332
Additions		—		(1,166)		(1,166)
Favorable lease terms December 31, 2019	$	83,716	$	(80,550)	$	3,166
Additions		—		(1,166)		(1,166)
Favorable lease terms December 31, 2020	$	83,716	$	(81,716)	$	2,000

Amortization of Favorable Lease Terms

		Year Ended
		December 31, 2020		December 31, 2019		December 31, 2018
Favorable lease terms	$	(1,166)	$	(1,166)	$	(3,748)
Total	$	(1,166)	$	(1,166)	$	(3,748)

Aggregate Amortizations of Intangible Assets

The aggregate amortization of the intangibles for the years ended December 31, 2021 and 2022 is estimated to be as follows:

Year		Amount
2021	$	1,166
2022		834
Total	$	2,000