Share-Based Compensation and Benefit Plans (Profit Sharing and Savings Plan) (Narrative) (Detail) - Profit sharing and savings plan [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-Based Compensation and Benefit Plans
Profit sharing and savings plan, employer discretionary contribution			$ 0	$ 0
Profit sharing and savings plan, cost recognized	$ 8,000	$ 7,500	$ 22,600	$ 20,100
Employee's first 2% of contributed wages [Member]
Share-Based Compensation and Benefit Plans
Profit sharing and savings plan, Company match			100.00%
Employee's next 4% of contributed wages [Member]
Share-Based Compensation and Benefit Plans
Profit sharing and savings plan, Company match			25.00%