Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance		$ 14,095	$ 13,468	$ 11,741	$ 11,172
Valuation Allowances and Reserves, Charged to Cost and Expense		956	301	5,514
Valuation Allowances and Reserves, Adjustments	[1]	$ (329)	$ 1,426	$ (4,945)

[1] Primarily accounts receivable written off during the period.