Debt (Aggregate Borrowing Information) (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Line of Credit Facility [Line Items]
Unused credit lines	$ 530,900,000	$ 308,700,000
Financial Services [Member]
Line of Credit Facility [Line Items]
Available credit lines	360,000,000	310,000,000
Unused credit lines	$ 28,379,000	$ 42,123,000
Weighted-average interest rate	2.89%	2.65%