Commitments and Contingencies
 3 Months Ended
Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]  
Commitments and Contingencies
Commitments and Contingencies
Operating Lease Commitments and Expected Sublease Receipts    
As of March 31, 2018, our principal obligations consisted of obligations outstanding under non-cancellable operating leases that expire at various dates through 2029. The following table represents our non-cancellable minimum lease payments, net of future expected sublease payments to be received under non-cancellable subleases, remaining as of March 31, 2018 (in thousands):
Period Ending
 
Operating Lease Commitments
 
Expected Sublease Receipts
 
Net
Remainder of 2018
 
$
33,177

 
$
(6,793
)
 
$
26,384

2019
 
41,480

 
(10,606
)
 
30,874

2020
 
43,138

 
(7,113
)
 
36,025

2021
 
43,603

 
(1,180
)
 
42,423

2022
 
43,216

 
(597
)
 
42,619

Thereafter
 
176,759

 
(121
)
 
176,638

Total
 
$
381,373

 
$
(26,410
)
 
$
354,963


Contractual Commitments
Our contractual commitments are associated with agreements that are enforceable and legally binding and that specify all significant terms, including fixed or minimum services to be used, fixed, minimum or variable price provisions and the approximate timing of the transaction. Obligations under contracts that we can cancel without a significant penalty are not included. There have been no material changes in our contractual commitments compared to those discussed in Note 10 in our Annual Report on Form 10-K for the year ended December 31, 2017.
Legal Proceedings
We are subject to certain routine legal proceedings, as well as demands and claims that arise in the normal course of our business. We make a provision for a liability relating to legal matters when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. These provisions are reviewed and adjusted to reflect the impacts of negotiations, estimated settlements, legal rulings, advice of legal counsel and other information and events pertaining to a particular matter.
We are not aware of any pending legal proceedings that we believe, individually or in the aggregate, would be expected to have a material adverse effect on our business, operating results, or financial condition. We may, in the future, be party to litigation arising in the ordinary course of business, including claims that we allegedly infringe upon third party intellectual property rights. Such claims, even if not meritorious, could result in the expenditure of significant financial and management resources.