Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 24, 2020
Entity Listings [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	001-33388
Entity Registrant Name	CAI International, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3109229
Entity Address, Address Line One	Steuart Tower, 1 Market Plaza, Suite 2400
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94105
City Area Code	415
Local Phone Number	788-0100
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		17,506,453
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Amendment Flag	false
Entity Central Index Key	0001388430
Common Stock [Member]
Entity Listings [Line Items]
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	CAI
Security Exchange Name	NYSE
Series A Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock [Member]
Entity Listings [Line Items]
Title of 12(b) Security	8.50% Series A Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock, par value $0.0001 per share
Trading Symbol	CAI-PA
Security Exchange Name	NYSE
Series B Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock [Member]
Entity Listings [Line Items]
Title of 12(b) Security	8.50% Series B Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock, par value $0.0001 per share
Trading Symbol	CAI-PB
Security Exchange Name	NYSE