Debt and Capital Lease Obligations (Details) (USD $)	6 Months Ended		6 Months Ended		6 Months Ended			6 Months Ended		6 Months Ended			6 Months Ended			3 Months Ended	6 Months Ended		6 Months Ended			6 Months Ended		6 Months Ended			6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Revolving Credit Facility [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Jun. 30, 2013 Revolving Credit Facility [Member] CAI Rail Inc [Member]	Dec. 31, 2012 Revolving Credit Facility [Member] CAI Rail Inc [Member]	Jun. 30, 2013 Term Loan [Member]	Jun. 30, 2013 Term Loan [Member] Development Bank of Japan [Member]	Dec. 31, 2012 Term Loan [Member] Development Bank of Japan [Member]	Jun. 30, 2013 Term Loan [Member] Consortium of Banks [Member]	Dec. 31, 2012 Term Loan [Member] Consortium of Banks [Member]	Jun. 30, 2011 Term Loan [Member] Consortium of Banks [Member]	Jun. 30, 2013 Term Loan [Member] Consortium of Banks, Note Dated April 11, 2012 [Member]	Dec. 31, 2012 Term Loan [Member] Consortium of Banks, Note Dated April 11, 2012 [Member]	Jun. 30, 2011 Term Loan [Member] Eurodollar Rate [Member] Consortium of Banks [Member]	Jun. 30, 2013 Senior Secured Notes [Member]	Jun. 30, 2013 Senior Secured Notes [Member]	Dec. 31, 2012 Senior Secured Notes [Member]	Jun. 30, 2013 Asset Backed Warehouse Facility [Member]	Jun. 30, 2013 Asset Backed Notes [Member]	Dec. 31, 2012 Asset Backed Notes [Member]	Jun. 30, 2013 Collateralized Financing Obligations [Member]	Dec. 31, 2012 Collateralized Financing Obligations [Member]	Jun. 30, 2013 Swing Line Loans [Member]	Jun. 30, 2013 Standby Letters of Credit [Member]	Jun. 30, 2013 Letter of Credit [Member]	Jun. 30, 2013 Term Loan II [Member] Consortium of Banks [Member]	Jun. 30, 2013 Capital Lease Obligations [Member]
Debt [Abstract]
Current Outstanding	$ 68,280,000	$ 61,044,000	$ 0	$ 0	$ 0	$ 0		$ 2,600,000	$ 800,000	$ 7,500,000	$ 24,964,000		$ 9,940,000	$ 9,940,000		$ 8,240,000	$ 8,240,000	$ 8,240,000		$ 40,000,000	$ 17,100,000	$ 0	$ 0
Long-term Outstanding	1,067,488,000	888,990,000	223,000,000	160,000,000	41,469,000	41,469,000		34,400,000	6,600,000	115,625,000	230,651,000		124,290,000	129,260,000		90,640,000	90,640,000	94,760,000		342,875,000	151,050,000	95,189,000	75,200,000
Average Interest (in hundredths)			2.20%	3.00%	2.40%	2.50%		2.40%	2.70%	2.50%	3.30%		2.30%	2.50%		4.90%	4.90%	4.90%		3.40%	3.50%	1.00%	1.10%
Agreement Terminates			Mar. 31, 2018		Jun. 30, 2015			Apr. 30, 2018		Dec. 31, 2016			Apr. 30, 2017				Sep. 30, 2022			Mar. 31, 2028		Nov. 30, 2016
Maximum credit commitment			760,000,000		85,000,000					300,000,000			142,000,000											10,000,000	15,000,000
Maximum amount credit facility might be increased			960,000,000										200,000,000
Percentage of aggregate principal to prepay, minimum (in hundredths)																10.00%
Principal amount of loan								10,000,000											171,000,000	229,000,000							30,000,000
Revolving Credit Facility [Abstract]
Number of business days short term borrowings payable, Maximum																								10 days
Availability borrowing capacity			536,900,000		43,500,000
Letters of credit outstanding																										100,000
Term Loans [Abstract]
Term of loan								5 years		5 years			5 years
Number of quarterly installments								19																			19
Quarterly payments of principal								200,000		1,900,000																	500,000
Debt instrument final payment								6,200,000																			21,500,000
Proceeds used to repay credit facility	124,400,000
Proceeds used for working capital purposes																			229,000,000
Amount outstanding under the facility							123,100,000	37,000,000		249,400,000			134,200,000			98,900,000	98,900,000
Periodic payment of principal balance										125,000,000
Amortization term of facility								6 years
Terms										The Base Rate is defined as the highest of (i) the federal funds rate plus 1/2 of 1.0%, (ii) the prime rate (as published in The Wall Street Journal), and (iii) the Eurodollar rate (for three-month loans) plus 1.0%.
Basis spread on variable rate (in hundredths)												0.50%			1.00%
Periodic payments specified as percentage of drawn amount (in hundredths)													1.75%
Long term debt maturity [Abstract]
Long-term debt	1,067,488,000	888,990,000														103,000,000	103,000,000			9,800,000		95,200,000
Capital Lease Obligations [Abstract]
Average fixed and floating interest rates (in hundredths)	2.50%																					1.00%
Maturity date range start																						Jun. 30, 2015						Sep. 30, 2013
Maturity date range end																						Nov. 30, 2016						Jun. 30, 2019
Estimated future principal and interest payments under capital lease obligations [Abstract]
Capital lease obligation	$ 6,200,000