Restructuring and Other Charges - Summary of Cumulative Amounts Incurred for 2015 Restructuring Costs (Details) $ in Thousands	Jun. 30, 2017 USD ($)
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	$ 437,160
Lease Abandonments
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	230,525
Involuntary Terminations
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	173,518
Outside Services
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	24,368
Other Restructuring Related
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	$ 8,749