Restructuring and Severance Charges (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring and Severance Charges [Abstract]
Cash charges associated with restructuring	$ 22,100
Employee severance	20,100
Other related restructuring charges	2,000
Liability in accrued payroll and other employee expenses	15,500
Restructuring, severance and impairment charges incurred	70,686	$ 0	$ 0
Non-cash impairment charges	(48,551)	$ 0	$ 0
Amounts paid	(6,673)
Adjustments	0
Restructuring charges	$ 15,462

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

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