Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Cash and cash equivalents	$ 629,551	$ 339,629
Current assets	1,270,194	942,927
Total assets	5,953,677	6,515,628
Current liabilities	1,106,168	1,070,804
Liabilities	$ 3,661,459	$ 3,699,182
Preferred Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized	49,889,000	49,889,000
Preferred Stock, Shares Issued	0
Preferred Stock, Shares Outstanding	0	0
Treasury Stock, Shares	17,627,000	16,008,000
Class A Common Stock
Common Stock, Par or Stated Value Per Share	$ 0.004	$ 0.004
Common Stock, Shares Authorized	700,000,000	700,000,000
Common Stock, Shares, Issued (in shares)	136,834,000	135,583,000
Common Stock, Shares, Outstanding (in shares)	119,207,000	119,575,000
Class B Common Stock
Common Stock, Par or Stated Value Per Share	$ 0.004	$ 0.004
Common Stock, Shares Authorized	175,000,000	175,000,000
Common Stock, Shares, Issued (in shares)	90,813,000	90,831,000
Common Stock, Shares, Outstanding (in shares)	90,813,000	90,831,000
Variable Interest Entity, Primary Beneficiary
Cash and cash equivalents	$ 215,908	$ 157,003
Current assets	392,899	346,125
Total assets	657,761	948,632
Current liabilities	191,165	142,343
Liabilities	$ 317,954	$ 257,199