Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Consolidated net income (loss)	$ 84,943	$ 279,866	$ 81,729
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(86)	(13,543)	15,779
Available-for-sale securities			(927)
Benefit plans	(12,928)
Total other comprehensive income (loss), net of tax	(13,014)	(13,543)	14,852
Comprehensive income (loss)	71,929	266,323	96,581
Less: Comprehensive income (loss) from continuing operations attributable to noncontrolling interest in subsidiaries, net of tax	24,859	28,136	38,306
Less: Comprehensive income (loss) from discontinued operations attributable to noncontrolling interest in subsidiaries, net of tax		52,353	(5,913)
Less: Comprehensive income (loss) attributable to noncontrolling interest in subsidiaries, net of tax	24,859	80,489	32,393
Comprehensive income (loss) attributable to common stockholders	$ 47,070	$ 185,834	$ 64,188