Difference Between Statutory Federal Income Tax Rate and Effective Income Rate (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory tax rate	21.00%	21.00%	35.00%
State income taxes - net of the federal income tax benefit	1.70%	1.20%	1.90%
Goodwill impairment	(0.70%)	(6.90%)
Permanent differences	(0.50%)	(0.60%)	(1.30%)
Tax effects of tax reform		(1.30%)	66.70%
Share-based payments	(0.70%)	(0.10%)	3.60%
Acquisition related differences			(3.30%)
Valuation allowance	(0.80%)	(3.70%)
State deferred tax remeasurement	(1.10%)	2.30%
Other differences, net	0.80%	0.60%	(0.80%)
Effective tax rate	19.70%	12.50%	101.80%