Benefit Plans - Stock Options Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Shares outstanding at beginning of year (in shares)	1,051,787	446,980	732,489
Shares in connection with acquisition (in shares)	3,130,171	1,803,165	0
Shares exercised (in shares)	(716,920)	(975,325)	0
Shares forfeited or expired (in shares)	(11,522)	(223,033)	(285,509)
Shares outstanding at end of year (in shares)	3,453,516	1,051,787	446,980
Shares exercisable at year-end (in shares)	3,339,517	604,003	446,980
Weighted Average Exercise Price
Weighted average exercise price, outstanding at beginning of year (in usd per share)	$ 7	$ 13	$ 14
Weighted average exercise price in connection with acquisition (in usd per share)	8	5	0
Weighted average exercise price, exercised (in usd per share)	7	5	0
Weighted average exercise price, forfeited or expired (in usd per share)	8	14	16
Weighted average exercise price, outstanding at end of year (in usd per share)	8	7	13
Weighted average exercise price, exercisable at year-end (in usd per share)	$ 8	$ 7	$ 13