Debt (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended										12 Months Ended
	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Unsecured Letter Of Credit Facility [Member]	Dec. 31, 2012 Unsecured Letter Of Credit Facility [Member]	Dec. 31, 2013 Letter Of Credit [Member]	Dec. 31, 2012 Letter Of Credit [Member]	Dec. 31, 2013 Financial Services [Member]	Dec. 31, 2012 Financial Services [Member]	Dec. 31, 2011 Financial Services [Member]	Dec. 31, 2013 Financial Services [Member] Repurchase Agreement [Member]	Jan. 31, 2014 Financial Services [Member] Repurchase Agreement [Member] Subsequent Event [Member]
Debt Instrument
Letters of credit outstanding, amount	$ 179,200,000	$ 183,100,000	$ 179,200,000		$ 124,400,000	$ 124,600,000	$ 58,700,000	$ 54,500,000
Line of credit facility, expiration date					Sep. 01, 2014							Sep. 12, 2014
Maximum borrowing capacity					150,000,000				150,000,000	150,000,000	2,500,000	150,000,000	99,750,000
Line of credit facility, initiation date												Jan. 09, 2014
Financial Services debt	138,795,000	105,664,000	138,795,000									105,700,000
Long-term debt principal total		2,071,892,000
Long-term debt, maturities, repayments of principal, 2014		0
Long-term debt, maturities, repayments of principal, 2015		333,600,000
Long-term debt, maturities, repayments of principal, 2016		465,200,000
Long-term debt, maturities, repayments of principal, 2017		123,000,000
Long-term debt, maturities, repayments of principal, 2018		0
Long-term debt, maturities, repayments of principal, thereafter		1,200,000,000
Extinguishment of debt, amount		461,400,000	592,400,000	323,900,000
Loss on debt retirements	$ 32,100,000	$ 26,930,000	$ 32,071,000	$ 5,638,000
Days from time of origination of loan to point of sale to third party		30 days