Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net Income (Loss) to Common Stockholders, Basic EPS	$ 34,542	$ (49,997)	$ (153,576)	$ (72,265)
Net Income (Loss) Income to Common Stockholders, Effect of dilutive securities	305
Net Income (Loss) Income to Common Stockholders, Diluted EPS	$ 34,847	$ (49,997)	$ (153,576)	$ (72,265)
Average Shares, Basic EPS	98,977	98,635	98,769	98,586
Average Shares, Effect of dilutive securities	4,548
Average Shares, Diluted EPS	103,525	98,635	98,769	98,586
Income (Loss) per Share, Basic EPS	$ 0.35	$ (0.51)	$ (1.55)	$ (0.73)
Income (Loss) per Share, Effect of dilutive securities	(0.01)
Income (Loss) per Share, Diluted EPS	$ 0.34	$ (0.51)	$ (1.55)	$ (0.73)