Summary of Significant Accounting Policies - Leasing Equipment (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018
Property, Plant and Equipment [Line Items]
Net gain (loss) on sale of leasing equipment	$ 10,749,000	$ 10,263,000	$ 9,639,000	$ 5,161,000	$ (4,261,000)	$ (12,319,000)	$ (1,930,000)	$ (1,837,000)	$ 35,812,000	$ (20,347,000)	$ 2,013,000
Property Subject to or Available for Operating Lease, Net	8,364,484,000				7,370,519,000				8,364,484,000	7,370,519,000
Property Available for Operating Lease, Net	509,500,000				524,900,000				$ 509,500,000	$ 524,900,000
Dry Container Units 20 Foot
Property, Plant and Equipment [Line Items]
Useful Lives									13 years	13 years
Residual values from date of manufacture	1,000				1,000				$ 1,000	$ 1,000
Dry Container Units 40 Foot [Member]
Property, Plant and Equipment [Line Items]
Useful Lives									13 years	13 years
Residual values from date of manufacture	1,200				1,200				$ 1,200	$ 1,200
Dry Container Units 40 Foot High Cube [Member]
Property, Plant and Equipment [Line Items]
Useful Lives									13 years	13 years
Residual values from date of manufacture	1,400				1,400				$ 1,400	$ 1,400
Refrigerated Container Units 20 Foot [Member]
Property, Plant and Equipment [Line Items]
Useful Lives									12 years	12 years
Residual values from date of manufacture												$ 2,350
Refrigerated Container Units 40 Foot High Cube [Member]
Property, Plant and Equipment [Line Items]
Useful Lives									12 years	12 years
Residual values from date of manufacture												3,350
Special Container Units 40 Foot Flat Rack [Member]
Property, Plant and Equipment [Line Items]
Residual values from date of manufacture												1,700
Special Container Units 40 Foot Open Top [Member]
Property, Plant and Equipment [Line Items]
Residual values from date of manufacture												$ 2,300
Dry container units
Property, Plant and Equipment [Line Items]
Property Subject to or Available for Operating Lease, Net	5,941,097,000				4,839,648,000				$ 5,941,097,000	$ 4,839,648,000
Refrigerated container units
Property, Plant and Equipment [Line Items]
Property Subject to or Available for Operating Lease, Net	1,897,385,000				2,037,952,000				1,897,385,000	2,037,952,000
Special container units
Property, Plant and Equipment [Line Items]
Property Subject to or Available for Operating Lease, Net	287,869,000				265,666,000				$ 287,869,000	$ 265,666,000
Tank Container Units [Member]
Property, Plant and Equipment [Line Items]
Useful Lives									20 years	20 years
Residual values from date of manufacture	3,000				3,000				$ 3,000	$ 3,000
Property Subject to or Available for Operating Lease, Net	105,821,000				107,933,000				$ 105,821,000	$ 107,933,000
Chassis [Member]
Property, Plant and Equipment [Line Items]
Useful Lives									20 years	20 years
Residual values from date of manufacture	1,200				1,200				$ 1,200	$ 1,200
Property Subject to or Available for Operating Lease, Net	$ 132,312,000				$ 119,320,000				132,312,000	119,320,000
Long Lived Assets Held-for-sale, Name [Domain]
Property, Plant and Equipment [Line Items]
Net gain (loss) on sale of leasing equipment									3,000	(19,399,000)	0
Equipment, net of selling costs [Member]
Property, Plant and Equipment [Line Items]
Net gain (loss) on sale of leasing equipment									$ 35,809,000	$ (948,000)	$ 2,013,000