Schedule II Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts, 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]
Beginning balance	$ 7,308	$ 4,610	$ 2,645
Additions	2,190	3,766	2,932
Deductions	(4,320)	(1,068)	(967)
Ending balance	$ 5,178	$ 7,308	$ 4,610