Significant Accounting Policies Changes in the allowance for doubtful accounts receivable (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year		$ 2,563	$ 3,698	$ 5,339
Additions charged to earnings		1,442	637	428
Uncollectible receivables written off, net of recoveries	(2,069)	(1,112)	(1,772)
Balance at end of year	$ 3,698	$ 2,893	$ 2,563	$ 3,698