Deferred revenue (Tables)

12 Months Ended

Dec. 31, 2018

Deferred Revenue Disclosure [Abstract]

Deferred Revenue

	2018			2017
Deferred revenue on time charters	$	22,318		$	26,907
Deferred interest on lease receivable		410,481			355,451
Other deferred revenue		—			1,690
Deferred revenue		432,799			384,048
Current portion of deferred revenue		(55,915	)		(55,367	)
Deferred revenue	$	376,884		$	328,681