Earnings Per Share - Calculation of Basic Earnings Per Share from Continuing and Discontinued Operations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic earnings (loss) per share:
Net income (loss) from continuing operations available to common stockholders	$ (3,529)	$ 31,610	$ 71,950	$ 95,609
Net income (loss) from discontinued operations available to common stockholders		87,254		117,068
Net income (loss) available to common stockholders	$ (3,529)	$ 118,864	$ 71,950	$ 212,677
Basic weighted-average shares of common stock outstanding	346,060	327,932	341,940	319,027
Continuing operations	$ (0.01)	$ 0.10	$ 0.21	$ 0.30
Discontinued operations		0.26		0.37
Basic earnings (loss) per share	$ (0.01)	$ 0.36	$ 0.21	$ 0.67