Earnings Per Share - Calculation of Basic Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Basic earnings (loss) per share:
Net income (loss) available to common stockholders	$ 21,768	$ 14,467	$ 39,983	$ 26,972
Basic weighted-average shares of common stock outstanding	286,840	275,997	285,129	274,895
Basic earnings (loss) per share	$ 0.08	$ 0.05	$ 0.14	$ 0.10