Debt (Details Textual) (USD $)	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Debt (Textual) [Abstract]
Borrowing under revolving credit facility exclusive of letters of credit	$ 0.0
Letter of credit maturing current year	700,000
Convertible subordinated notes [Member]
Debt (Textual) [Abstract]
Interest rate on notes	3.875%
Date before which notes can't be redeemed	Jun. 01, 2018
Capital in excess of par value related to the convertible subordinated notes' conversion options	92,800,000	92,800,000
Effective annual interest rate based upon the estimated market interest rate	8.42%
Conversion price of convertible subordinated notes (in dollars per share)	$ 51.31
Number of shares issuable in exchange of Convertible Subordinated Notes	8,770,220
TILC warehouse facility [Member]
Debt (Textual) [Abstract]
Revolving credit facility	475,000,000
Maturity date of credit arrangements	February, 2013
Availability of the revolving credit facility	183,600,000
TILC warehouse facility	291,400,000
Interest at a defined index rate plus a margin for advances under the facility	2.27%
Number of installments payable for amounts outstanding at maturity, absent renewal	3
Installment payable date, installment one	August 2013
Installment payable date, installment two	February 2014
Installment payable date, installment three	August 2014
Corporate Revolving Credit Facility [Member]
Debt (Textual) [Abstract]
Revolving credit facility	425,000,000
Maturity date of credit arrangements	2016-10-20
Used revolving credit facility for letter of credit	70,900,000
Availability of the revolving credit facility	$ 354,100,000
Amended credit facility, description of variable rate reference rate basis	LIBOR
Percentage points added to LIBOR to compute Interest rates on the amended credit facility	150.00%
Amended credit facility, description of variable rate reference rate basis, alternative computation	prime
Percentage points added to prime to compute Interest rates on the amended credit facility, alternative computation	50.00%