CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Current assets
Accounts receivable, allowance for doubtful accounts	$ 1,455	$ 1,440
Rental equipment net of accumulated depreciation	2,299,955	2,004,961
Rental equipment, accumulated depreciation	575,866	505,546
Net investment in direct finance leases	444,741	246,450
Intangible assets, accumulated amortization	4,946	3,407
Furniture, fixtures and equipment, accumulated depreciation	3,303	3,201
Current liabilities
Current portion of debt	194,563	132,049
Debt	$ 1,777,420	$ 1,570,773
Stockholders' equity
Common stock, shares issued	19,306,202	20,390,622
Common stock, shares outstanding	19,306,202	20,390,622
Variable Interest Entity, Primary Beneficiary [Member]
Current assets
Cash	$ 23,779	$ 20,685
Rental equipment net of accumulated depreciation	73,110	61,842
Net investment in direct finance leases	9,375	4,423
Current liabilities
Current portion of debt	39,302	22,549
Debt	$ 65,717	$ 72,727
Series A Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock [Member]
Stockholders' equity
Preferred stock, dividend rate	8.50%	8.50%
Preferred stock, shares issued	2,199,610	0
Preferred stock, shares outstanding	2,199,610	0
Series B Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock [Member]
Stockholders' equity
Preferred stock, dividend rate	8.50%	8.50%
Preferred stock, shares issued	1,955,000	0
Preferred stock, shares outstanding	1,955,000	0