Organization and Summary of Significant Accounting Policies - Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ 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
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basic EPS impact from tax benefit from US tax reform										$ 1.92
Diluted EPS impact from tax benefit from US tax reform										$ 1.91
Weighted average number diluted shares excluded from calculation											2,303,000
Income (numerator):
Net income - basic and diluted	$ 197,738	$ 314,169	$ 242,464	$ 233,946	$ 841,914	$ 10,621	$ (63,557)	$ 469	$ 988,317	$ 789,447	$ (399,679)
Weighted average shares - basic									371,854,000	371,066,000	370,380,000
Non-vested restricted stock									2,984,000	2,702,000	0	[1]
Weighted average shares - diluted									374,838,000	373,768,000	370,380,000
Net income per share:
Basic (in dollars per share)	$ 0.53	$ 0.84	$ 0.65	$ 0.63	$ 2.27	$ 0.03	$ (0.17)	$ 0.00	$ 2.66	$ 2.13	$ (1.08)
Diluted (in dollars per share)	$ 0.53	$ 0.84	$ 0.65	$ 0.63	$ 2.25	$ 0.03	$ (0.17)	$ 0.00	$ 2.64	$ 2.11	$ (1.08)

[1] For the year ended December 31, 2016, the Company had a net loss and therefore the potential dilutive effect of approximately 2,303,000 weighted average non-vested restricted shares were not included in the calculation of diluted net loss per share because to do so would have been anti-dilutive to the computation.