Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Consolidated net income (loss)	$ 24,930	$ 2,560	$ 85,521	$ 111,499
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	8,190	(8,241)	(8,375)	(10,476)
Benefit plans			2,236
Total other comprehensive income (loss), net of tax	8,190	(8,241)	(6,139)	(10,476)
Comprehensive income (loss)	33,120	(5,681)	79,382	101,023
Less: Comprehensive income (loss) attributable to noncontrolling interest in subsidiaries, net of tax	6,574	5,110	23,891	38,260
Comprehensive income (loss) attributable to common stockholders	$ 26,546	$ (10,791)	$ 55,491	$ 62,763