Per Share Information - Basic and Diluted Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Amounts attributable to common stock:
Net income from continuing operations	$ 16,562	$ 32,007	$ 37,058	$ 79,696
Net income from discontinued operations		14,102		19,897
Net income attributable to common stock	$ 16,562	$ 46,109	$ 37,058	$ 99,593
Weighted average shares:
Weighted average shares outstanding for basic earnings per share	156,128	213,047	159,577	214,257
Effect of dilutive stock options	2	12	2	12
Weighted average shares outstanding for diluted earnings per share	156,130	213,059	159,579	214,269