Debt (Details Textual) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014 debt_holders	Dec. 31, 2013
Recourse | Corporate revolving credit facility
Debt (Textual) [Abstract]
Revolving credit facility	$ 425.0
Maturity date of credit facility	Oct. 20, 2016
Used revolving credit facility for letters of credit	67.0
Availability of the revolving credit facility	358.0
Borrowing under revolving credit facility exclusive of letters of credit	0
Letter of credit expiring in current year	65.5
Credit facility, description of variable rate reference rate basis	Libor
Percentage points added to Libor to compute interest rates on the credit facility	1.50%
Credit facility, description of variable rate reference rate basis, alternative computation	prime
Percentage points added to prime to compute interest rates on the credit facility, alternative computation	0.50%
Recourse | Convertible Subordinated Notes
Debt (Textual) [Abstract]
Capital in excess of par value related to the Convertible Subordinated Notes' conversion options	92.8	92.8
Date through which debt discount is being amortized	Jun. 01, 2018
Effective annual interest rate yield based upon the estimated market interest rate	8.42%
Percentage of conversion price at which Convertible Subordinated Notes are convertible	130.00%
Conversion price of Convertible Subordinated Notes (in dollars per share)	$ 50.69
Number of holders who have elected to convert their convertible debt	0
Non-recourse | TILC warehouse facility
Debt (Textual) [Abstract]
Revolving credit facility	475.0
Availability of the revolving credit facility	341.8
Credit facility, amount outstanding	$ 133.2
Interest at a defined index rate plus a margin for advances under the facility	1.92%
Maturity date	June 2015
Number of installments payable for amounts outstanding at maturity, absent renewal	3
Installment payable date, installment one	December 2015
Installment payable date, installment two	June 2016
Installment payable date, installment three	December 2016