Short-Term Borrowings (Details) (Credit Agreement [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 entity	Nov. 30, 2012
Minimum [Member]
Short-term Debt [Line Items]
Ratio of Consolidated Fund Indebtedness to Earning Before Interest Taxes Depreciation Amortization	1.0
Fixed Charge Coverage Ratio	1.0
Maximum [Member]
Short-term Debt [Line Items]
Ratio of Consolidated Fund Indebtedness to Earning Before Interest Taxes Depreciation Amortization	2.5
Fixed Charge Coverage Ratio	1.2
Bank of America, N.A. [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 75.0
Line of Credit Facility, Overdraft Facility		5.0
Number of Indirect Subsidiaries Guaranteeing Line of Credit Facility	3
Number of Borrowers, Line of Credit Facility	3
Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Remaining borrowing capacity under line of credit	69.1
Amount outstanding on line of credit	2.8
Letters of Credit Outstanding, Amount	3.1
Revolving Credit Facility [Member] | Minimum [Member]
Short-term Debt [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	1.42%
Revolving Credit Facility [Member] | Maximum [Member]
Short-term Debt [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	1.78%
Revolving Credit Facility [Member] | Bank of America, N.A. [Member] | Minimum [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.15%
Revolving Credit Facility [Member] | Bank of America, N.A. [Member] | Maximum [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.225%
Revolving Credit Facility [Member] | Bank of America, N.A. [Member] | Applicable Rate [Member] | Minimum [Member]
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Revolving Credit Facility [Member] | Bank of America, N.A. [Member] | Applicable Rate [Member] | Maximum [Member]
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%
Revolving Credit Facility [Member] | Bank of America, N.A. [Member] | Base Rate [Member] | Minimum [Member]
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.25%
Revolving Credit Facility [Member] | Bank of America, N.A. [Member] | Base Rate [Member] | Maximum [Member]
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Revolving Credit Facility [Member] | TD Bank [Member]
Short-term Debt [Line Items]
Letters of Credit Outstanding, Amount	$ 0.4