Deposits - Schedule of Deposits by Type (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Banking and Thrift [Abstract]
Interest-bearing demand deposits	$ 4,821,252	$ 4,514,113
Money market accounts	9,121,283	8,237,291
Savings accounts	683,366	828,914
Time deposits	4,273,642	3,640,623
Total deposits	$ 18,899,543	$ 17,220,941

No definition available.

Name:	us-gaap_BankingAndThriftAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Total amount of interest-bearing domestic deposit liabilities, which may include brokered, retail, demand, checking, notice of withdrawal, money market and other interest-bearing deposits.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_InterestBearingDepositLiabilitiesDomestic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest-bearing domestic money market demand account deposit liabilities.

+ References

+ Details

Name:	us-gaap_InterestBearingDomesticDepositMoneyMarket
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest-bearing domestic negotiable order of withdrawal (NOW) demand deposit liabilities.

+ References

+ Details

Name:	us-gaap_InterestBearingDomesticDepositNegotiableOrderOfWithdrawalNOW
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest-bearing domestic savings deposit liabilities. Saving deposits bear interest and have no stated maturity.

+ References

+ Details

Name:	us-gaap_InterestBearingDomesticDepositSavings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest-bearing domestic time deposits. Time deposits bear interest for a fixed, stated period of time and include certificate of deposits and individual retirement accounts.

+ References

+ Details

Name:	us-gaap_InterestBearingDomesticDepositTimeDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant