Schedule II - Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Reserves for Accounts Receivable [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 4,555		$ 5,232		$ 10,579
Charged to operations	15,599	[1]	16,165	[1]	22,657	[1]
Other	(47)	[2]	(420)	[2]	(301)	[2]
Deductions	(16,300)	[3]	(16,422)	[3]	(27,703)	[3]
Balance at end of period	3,807		4,555		5,232
Deferred Tax Asset Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	433		7,407		7,086
Charged to operations	(3)	[4]	(6,974)	[4]	465	[4]
Other	0		0		0
Deductions	0		0		(144)
Balance at end of period	$ 430		$ 433		$ 7,407

[1] Amounts represent charges to bad debt expense and reductions to revenue for increases to the allowance for doubtful accounts and to the reserve for cash-basis customers.

[2] Amounts represent write-offs of account receivables previously reserved.

[3] Amounts represent cash collections from customers for accounts previously reserved and write-offs of accounts receivable recorded against the allowance for doubtful accounts or the reserve for cash-basis customers.

[4] Amount represents the reversal of a tax valuation allowance related to NOL carryforwards not expected to be realized.