Leases - Total Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Finance Lease Cost:
Amortization of Right-of-Use Assets	$ 465
Interest on Lease Liabilities	114
Total Finance Lease Cost	579
Operating Lease Cost	29,285
Sublease Receipts	(732)
Total Lease Cost	29,864
Operating Lease Cost Classified within Operating Expenses
Finance Lease Cost:
Operating Lease Cost	29,213
Operating Lease Cost Classified within Restructuring Expenses, Net
Finance Lease Cost:
Operating Lease Cost	$ 804