Debt (Narrative) (Details)	12 Months Ended														12 Months Ended		0 Months Ended								12 Months Ended					12 Months Ended			12 Months Ended							12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2014 Secured Notes Through One Term Asset-backed Securitization Transaction [Member] Secured Debt [Member] USD ($)	Dec. 31, 2013 Secured Notes Through One Term Asset-backed Securitization Transaction [Member] Secured Debt [Member] USD ($)	Dec. 31, 2013 Secured Notes Sold Through Term Asset-backed Securitization Transaction [Member] Secured Debt [Member] USD ($)	Dec. 31, 2014 Term Asset-Backed Securitization VIEs [Member] Secured Debt [Member] USD ($)	Dec. 31, 2013 Term Asset-Backed Securitization VIEs [Member] Secured Debt [Member] USD ($)	Dec. 31, 2014 Medium-Term Notes Due 2019 [Member] USD ($)	Dec. 31, 2014 Medium-Term Notes Due 2017 1.55 rate [Member] [Member] USD ($)	Dec. 31, 2014 Medium-Term Notes Due 2018 [Member] USD ($)	Dec. 31, 2014 Senior Unsecured Notes Effective February 2009 [Member] Senior Notes [Member] USD ($)	Dec. 31, 2010 Senior Unsecured Notes Effective February 2009 [Member] Senior Notes [Member] USD ($)	Feb. 28, 2009 Senior Unsecured Notes Effective February 2009 [Member] Senior Notes [Member] USD ($)	Dec. 31, 2014 Credit Agreement [Member] Global Credit Facilities [Member]	Apr. 07, 2014 Line of Credit [Member] Credit Facility Maturing April 2019 [Member] USD ($)	Apr. 08, 2014 Line of Credit [Member] Credit Facility Maturing April 2017 [Member]	Apr. 13, 2012 Line of Credit [Member] Credit Facility Maturing April 2017 [Member] USD ($)	Apr. 13, 2012 Line of Credit [Member] Credit Facility Maturing April 2015 [Member] USD ($)	Sep. 13, 2013 Revolving Credit Facility [Member] Asset-Backed U.S. Commercial Paper Conduit Facility VIE [Member] Line of Credit [Member] USD ($)	Dec. 31, 2014 Financial Services Segment [Member] Medium-term Notes [Member] USD ($)	Dec. 31, 2013 Financial Services Segment [Member] Medium-term Notes [Member] USD ($)	Dec. 31, 2014 Financial Services Segment [Member] Medium-Term Notes Due 2019 [Member] Medium-term Notes [Member] USD ($)	Dec. 31, 2014 Financial Services Segment [Member] Medium-Term Notes Due 2017 1.55 rate [Member] [Member] Medium-term Notes [Member] USD ($)	Dec. 31, 2014 Financial Services Segment [Member] Medium-Term Notes Due 2018 [Member] Medium-term Notes [Member] USD ($)	Dec. 31, 2013 Financial Services Segment [Member] Medium-Term Notes Due 2018 [Member] Medium-term Notes [Member] USD ($)	Dec. 31, 2012 Financial Services Segment [Member] Medium-Term Notes Due 2018 [Member] Medium-term Notes [Member] USD ($)	Dec. 31, 2014 Financial Services Segment [Member] Medium-term Notes Matured [Member] Medium-term Notes [Member] USD ($)	Dec. 31, 2013 Financial Services Segment [Member] Medium-term Notes Matured [Member] Medium-term Notes [Member] USD ($)	Dec. 31, 2014 Financial Services Segment [Member] Credit Agreement [Member] Global Credit Facilities [Member]	Dec. 31, 2014 Financial Services Segment [Member] Revolving Credit Facility [Member] Asset-Backed U.S. Commercial Paper Conduit Facility VIE [Member] USD ($)	Dec. 31, 2013 Financial Services Segment [Member] Revolving Credit Facility [Member] Asset-Backed U.S. Commercial Paper Conduit Facility VIE [Member] USD ($)	Dec. 31, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Asset-backed Canadian Commercial Paper Conduit Facility [Member] Foreign Line of Credit [Member] USD ($)	Dec. 31, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Asset-backed Canadian Commercial Paper Conduit Facility [Member] Foreign Line of Credit [Member] CAD	Dec. 31, 2013 Variable Interest Entity, Not Primary Beneficiary [Member] Asset-backed Canadian Commercial Paper Conduit Facility [Member] Foreign Line of Credit [Member] USD ($)	Dec. 31, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Line of Credit [Member] Asset-backed Canadian Commercial Paper Conduit Facility [Member] Foreign Line of Credit [Member] USD ($)	Dec. 31, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Financial Services Segment [Member] Asset-backed Canadian Commercial Paper Conduit Facility [Member] Foreign Line of Credit [Member] USD ($)	Dec. 31, 2013 Variable Interest Entity, Not Primary Beneficiary [Member] Financial Services Segment [Member] Asset-backed Canadian Commercial Paper Conduit Facility [Member] Foreign Line of Credit [Member] USD ($)	Jun. 29, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Financial Services Segment [Member] Asset-backed Canadian Commercial Paper Conduit Facility [Member] Foreign Line of Credit [Member] CAD	Dec. 31, 2014 Unsecured Commercial Paper [Member]	Dec. 31, 2012 Unsecured Commercial Paper [Member]	Jan. 22, 2015 Subsequent Event [Member]	Jan. 22, 2015 Secured Notes Through One Term Asset-backed Securitization Transaction [Member] USD ($)
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate																																			2.03%							1.19%
Maturity date of Debt Instrument																	5 years 0 months 0 days																5 years 0 months 0 days	5 years 0 months 0 days						365 days
Weighted-average interest rate of commercial paper																																								0.30%	0.23%
Line of credit facility, maximum borrowing capacity																$ 675,000,000		$ 675,000,000	$ 675,000,000	$ 600,000,000														200,000,000					200,000,000
Line of credit facility, outstanding borrowings																															0	0
Face Amount of Finance Receivables Transferred																																	97,100,000		101,100,000		97,100,000	101,100,000
Proceeds from Sale of Finance Receivables																																			88,600,000	85,000,000	85,000,000	88,600,000
Long-term Debt, Current Maturities	1,011,315,000	1,176,140,000					366,900,000	334,600,000																													44,600,000	38,600,000
Debt instrument, face amount				850,000,000	650,000,000	89,500,000			600,000,000	400,000,000	888,000,000	600,000,000.0		600,000,000.0									600,000,000	400,000,000				500,000,000.0	400,000,000														700,000,000
Debt Instrument, Unamortized Discount (Premium), Net							200,000	500,000													3,600,000	1,500,000
Weighted average interest rate of asset-backed securitization transactions									2.40%	1.55%	6.80%			15.00%									2.40%	1.55%	6.80%			5.75%	5.25%
Repurchase Of Medium Term Notes																									22,600,000	23,000,000	16,600,000
Loss on debt extinguishment	3,942,000	4,947,000	4,323,000																						3,900,000	4,900,000	4,300,000
Debt Instrument, Repurchased Face Amount												$ 303,000,000	$ 297,000,000
Debt Instrument, Covenant, Debt to Equity Ratio, Maximum															0.65															10.0