v3.19.3
COMMITMENTS AND CONTINGENCIES - Operating and Finance Leases Narrative (Details)
$ in Thousands
 1 Months Ended 9 Months Ended
Jul. 31, 2019
USD ($)
ft²
renewal_option
Dec. 31, 2018
USD ($)
ft²
renewal_option
Sep. 30, 2019
USD ($)
Lessee, Lease, Description [Line Items]      
Operating lease renewal term     5 years
Operating lease option to terminate term     1 year
Total lease payments over term     $ 492,508
Leased area of office space executed but not yet commenced (in sq ft) | ft² 226,258    
Lease executed but not yet commenced, term 15 years 6 months    
Lease executed but not yet commenced, number of renewal options | renewal_option 2    
Lease executed but not yet commenced renewal term 5 years    
Lease executed but not yet commenced $ 42,700   $ 344,202
Minimum      
Lessee, Lease, Description [Line Items]      
Operating lease term     1 year
Maximum      
Lessee, Lease, Description [Line Items]      
Operating lease term     12 years
Lease executed but not yet commenced, option to terminate leased space (up to) 50.00%    
Equipment      
Lessee, Lease, Description [Line Items]      
Finance lease, remaining lease term     2 years
Oakland, California | Building      
Lessee, Lease, Description [Line Items]      
Operating lease term   12 years  
Operating lease renewal term   5 years  
Leased area of office space (in sq ft) | ft²   355,762  
Operating lease, number of renewal options | renewal_option   2  
Total lease payments over term   $ 276,000