Schedule II - Valuation and Qualifying Accounts (Details) - Summary of Valuation and Qualifying Accounts (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance for Doubtful Accounts [Member]
Valuation Allowance [Line Items]
Balance	$ 4,972		$ 3,166		$ 3,713
Charged to Costs and Expenses	6,228		5,226		2,455
Charged to other Accounts	5,462	[1]	3,420	[1]	3,002	[1]
Balance	5,738		4,972		3,166
Accrued Risk Reserves [Member]
Valuation Allowance [Line Items]
Balance	110,557		110,331		98,732
Charged to Costs and Expenses	62,083		57,515		67,900
Charged to other Accounts	65,896		57,289		56,301
Balance	$ 106,744		$ 110,557		$ 110,331

[1] Amounts written off, net of recoveries