Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 10,742	$ 13,149	$ 20,219
Additions charged to expense	1,408	2,041	3,881
Deductions	(2,888)	(4,448)	(10,951)
Balance at end of year	9,262	10,742	13,149
Valuation allowance for deferred tax asset
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	116,935	122,780	142,176
Additions charged to expense	21,232	636	15,921
Deductions	(5,543)	(6,481)	(35,317)
Balance at end of year	$ 132,624	$ 116,935	$ 122,780