Credit Facilities and Long-Term Debt, Revolving Credit Facility (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 250		$ 200
Expiration date	Mar. 31, 2018
Reduced unused fee (in hundredths)	0.25%
Additional available borrowing capacity	164.0
Financial covenants	At any time that our average borrowing availability is less than $25 million, the terms of our restated credit agreement provide for, among other provisions, a financial covenant requiring us, on a consolidated basis, to maintain specified levels of fixed charge coverage at the end of each fiscal quarter (rolling twelve months).
Direct Borrowings [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Margin on variable rate (in hundredths)	1.50%
Direct Borrowings [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Margin on variable rate (in hundredths)	2.00%
Index Loan [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Margin on variable rate (in hundredths)	0.50%
Index Loan [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Margin on variable rate (in hundredths)	1.00%
General Electric Capital Corporation Credit Facility [Member]
Line of Credit Facility [Line Items]
Outstanding borrowings under credit facility	59.1		21.4
Weighted average interest rate (in hundredths)	1.80%		2.00%
General Electric Capital Corporation Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Conditions for required financial covenants, maximum borrowing availability	25
General Electric Capital Corporation Credit Facility [Member] | Direct Borrowings [Member]
Line of Credit Facility [Line Items]
Outstanding borrowings under credit facility	56.0		18.0
Weighted average interest rate (in hundredths)	1.70%		1.70%
General Electric Capital Corporation Credit Facility [Member] | Index Loan [Member]
Line of Credit Facility [Line Items]
Outstanding borrowings under credit facility	3.0		3.4
Weighted average interest rate (in hundredths)	3.80%		3.80%
Average daily loan balance outstanding	4.5	4.9	4.1
GE Canada Finance Holding Company Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	10
Outstanding borrowings under credit facility	$ 0