Segment Information - Intersegment Activity Eliminated in Arriving at Consolidated Totals was Included in "All Other" Category (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 5,928,302	$ 5,632,187	$ 5,295,883
Income taxes (benefit)	590,160	915,556	743,284
Net income (loss)	1,918,080	1,408,306	1,315,114
Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Revenues	(41,285)	(43,941)	(48,625)
Expenses	(24,660)	(32,623)	(40,422)
Income taxes (benefit)	(4,371)	(4,606)	(3,338)
Net income (loss)	$ (12,254)	$ (6,712)	$ (4,865)