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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic earnings per share:
Net income	$ 133,934	$ 402,835	$ 384,349	$ 290,124	$ 185,517	$ 129,590	$ 65,600	$ 178,222	$ 1,211,242	$ 558,929	$ 186,678
Weighted-average common shares outstanding									435,374	431,885	428,822
Basic earnings per share (in USD per share)	$ 0.31	$ 0.92	$ 0.88	$ 0.67	$ 0.43	$ 0.30	$ 0.15	$ 0.41	$ 2.78	$ 1.29	$ 0.44
Diluted earnings per share:
Net income	$ 133,934	$ 402,835	$ 384,349	$ 290,124	$ 185,517	$ 129,590	$ 65,600	$ 178,222	$ 1,211,242	$ 558,929	$ 186,678
Shares used in computation:
Weighted-average common shares outstanding									435,374	431,885	428,822
Employee stock options									15,870	14,929	9,830
Weighted-average number of shares									451,244	446,814	438,652
Diluted earnings per share (in USD per share)	$ 0.30	$ 0.89	$ 0.85	$ 0.64	$ 0.41	$ 0.29	$ 0.15	$ 0.40	$ 2.68	$ 1.25	$ 0.43