Restructuring and Other Charges - Summary of Cumulative Amounts Incurred for 2015 Restructuring Costs (Details) $ in Thousands	Mar. 31, 2017 USD ($)
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	$ 429,106
Lease Abandonments
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	227,813
Involuntary Terminations
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	170,798
Outside Services
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	23,684
Other Restructuring Related
Restructuring Charges [Line Items]
Cumulative Amount Incurred to Date	$ 6,811