Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018 USD ($)
Document Period End Date	Dec. 31, 2018
Minimum [Member]
Aggregate range of reasonably possible losses on legal matters in excess of the accrued liability	$ 0
Maximum [Member]
Aggregate range of reasonably possible losses on legal matters in excess of the accrued liability	150,000,000
LR Trust v. SunTrust Banks, Inc., et al. [Member]
Loss Contingency, Damages Awarded, Value	$ 585,000