Organization and Summary of Significant Accounting Policies (Computation of Net Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic earnings per share:
Net income	$ 185,517	$ 129,590	$ 65,600	$ 178,222	$ 66,748	$ 51,517	$ 40,755	$ 27,658	$ 558,929	$ 186,678	$ 122,641
Weighted-average common shares outstanding									431,885	428,822	425,889
Basic earnings per share (in USD per share)	$ 0.43	$ 0.30	$ 0.15	$ 0.41	$ 0.16	$ 0.12	$ 0.10	$ 0.06	$ 1.29	$ 0.44	$ 0.29
Diluted earnings per share:
Net income	$ 185,517	$ 129,590	$ 65,600	$ 178,222	$ 66,748	$ 51,517	$ 40,755	$ 27,658	$ 558,929	$ 186,678	$ 122,641
Shares used in computation:
Weighted-average common shares outstanding									431,885	428,822	425,889
Employee stock options									14,929	9,830	10,567
Weighted-average number of shares									446,814	438,652	436,456
Diluted earnings per share (in USD per share)	$ 0.41	$ 0.29	$ 0.15	$ 0.40	$ 0.15	$ 0.12	$ 0.09	$ 0.06	$ 1.25	$ 0.43	$ 0.28