Asset Acquisition - Consideration Paid and Amortization Expense (Details) - USD ($) $ in Thousands		12 Months Ended
	May 06, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consideration:
Cash		$ 5,624	$ 10,272	$ 0
Recognized amounts of identifiable assets acquired:
Property and equipment — tractors and trailers		35,743	$ 11,731	$ 2,644
EH Trucking
Consideration:
Cash	$ 5,624
Value of AE common shares issued	392
Contingent consideration arrangement	431
Fair value of total consideration transferred	6,447
Recognized amounts of identifiable assets acquired:
Property and equipment — tractors and trailers	4,576
Shop, office and telecommunication equipment	20
Intangible assets — customer relationships	1,851
Total purchase price	$ 6,447
Amortization expense
2020		302
2021		283
2022		263
2023		244
2024		$ 227