Schedule II - Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 104		$ 141		$ 100
Charged to Costs and Expenses	1,823	[1]	1,991	[1]	2,808	[1]
Charged to Other Accounts	0		0		0
Deductions	(1,849)	[2]	(2,028)	[2]	(2,767)	[2]
Balance at End of Period	78		104		141
Valuation allowance-deferred tax asset
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	6,626		5,970		4,948
Charged to Costs and Expenses	6	[1]	656	[1]	1,022	[1]
Charged to Other Accounts	0		0		0
Deductions	0	[2]	0	[2]	0	[2]
Balance at End of Period	$ 6,632		$ 6,626		$ 5,970

[1] Adjustments to the valuation allowance for deferred taxes are recorded to adjust deferred tax asset to net realizable value.

[2] Uncollectible amounts reserved for or written-off.