Income Taxes - Components of the Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current provision for income taxes:
Federal																	$ 6,113	$ 31,935	$ 64,594
State																	2,018	3,645	10,529
Foreign																	10,451	7,322	4,675
Total current																	18,582	42,902	79,798
Deferred taxes benefit:
Federal																	(57,726)	12,795	(18,579)
State																	(4,164)	(3,404)	(3,564)
Foreign																	3,994	(734)	381
Total deferred																	(57,896)	8,657	(21,762)
Total provision for (benefit from) income taxes	$ 28,168		$ 20,865		$ (86,703)		$ (1,644)		$ 37,802		$ 8,545		$ 14,445		$ (9,233)		$ (39,314)	$ 51,559	$ 58,036

[1] Resulting from the adoption of ASU 2016-09, provision for (benefit from) income taxes for the first, second, third and fourth quarter of 2018 included excess tax benefits of $25.3 million, $20.1 million, $22.3 million and $7.8 million, respectively, of 2017 included $28.8 million, $19.1 million, $23.8 million and $38.3 million, respectively. In addition, provision for income taxes for the fourth quarter of 2017 included a provisional amount of $51.8 million in connection with the Tax Act enacted on December 22, 2017. See Note 10 for details. Benefit from income taxes for the second quarter of 2018 also included a benefit of $99.0 million in connection with our legal settlement with Cisco. See Note 14.