Discontinued Operations (Summarized Results from Discontinued Operations) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Discontinued Operations and Disposal Groups [Abstract]
Revenues	$ 4	$ 1,377	$ 13	$ 5,647
Cost of sales	(4)	(1,521)	(10)	(6,485)
Other operating expenses	1,043	(1,066)	989	(2,389)
Income (loss) from discontinued operations before income taxes	1,043	(1,210)	992	(3,227)
Gain (loss) on sale of assets before income taxes	100	(3,596)	100	(14,573)
Income tax benefit	86	2,758	555	7,536
Income (loss) from discontinued operations, net of taxes	$ 1,229	$ (2,048)	$ 1,647	$ (10,264)