Schedule II - Valuation and Qualifying Accounts (Valuation and Qualifying Accounts) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Sales returns and allowances [Member]
Balance at beginning of period	$ 6,500		$ 7,326		$ 6,406
Additions - charged to costs and expenses	355		(826)		920
Additions - charged to other accounts - describe	0		0		0
Deductions - describe	0		0		0
Balance at end of period	6,855		6,500		7,326
Allowance for doubtful accounts [Member]
Balance at beginning of period	6,661		6,447		6,403
Additions - charged to costs and expenses	8,919		8,499		8,043
Additions - charged to other accounts - describe	0		0		0
Deductions - describe	6,867	[1]	8,285	[1]	7,999	[1]
Balance at end of period	$ 8,713		$ 6,661		$ 6,447

[1] Uncollectable accounts written off.