Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 9,997	$ 12,455	$ 13,149
Additions charged to expense	6,797	430	3,197
Deductions	(2,422)	(2,888)	(3,891)
Balance at end of year	14,372	9,997	12,455
Valuation allowance for deferred tax asset
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	132,624	116,935	122,780
Additions charged to expense	6,523	21,232	636
Deductions	(12,052)	(5,543)	(6,481)
Balance at end of year	$ 127,095	$ 132,624	$ 116,935