Schedule II - Consolidated Valuation and Qualifying Accounts - K (Details) (Allowance for Doubtful Accounts, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance for Doubtful Accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 4,993		$ 4,883		$ 4,799
Charged to costs and expenses	1,183		1,187		1,129
Transferred from (to) allowance for accounts / notes receivable	0		0		46
Deductions	(1,532)	[1]	(1,077)	[1]	(1,091)	[1]
Balance at end of period	$ 4,644		$ 4,993		$ 4,883

[1] Uncollectible accounts written off, net of recoveries and adjustments to estimates for the allowance accounts.