XML 42 R31.htm IDEA: XBRL DOCUMENT v3.8.0.1
Recent Developments Including Mergers and Acquisitions - Additional Information (Detail)
$ in Millions
 9 Months Ended
Sep. 07, 2017
USD ($)
Jul. 31, 2017
shares
Sep. 30, 2017
First Bank & Trust Company [Member]      
Business Combination Separately Recognized Transactions [Line Items]      
Date of announcement regarding acquisition agreement Sep. 07, 2017    
Total assets acquired $ 280    
Loans 258    
Deposits 244    
Equity capital $ 36    
Expected date of completion of transaction 2018-01    
First Bank of Chandler [Member]      
Business Combination Separately Recognized Transactions [Line Items]      
Date of announcement regarding acquisition agreement Sep. 07, 2017    
Total assets acquired $ 90    
Loans 82    
Deposits 79    
Equity capital $ 11    
Expected date of completion of transaction 2018-01    
COMMON STOCK [Member]      
Business Combination Separately Recognized Transactions [Line Items]      
Stock split description     On July 31, 2017, the Company completed a two-for-one stock split of the Company’s outstanding shares of common stock.
Stock split conversion ratio   2  
Stock payable in form of dividend, payable date   Jul. 31, 2017  
Stock payable in form of dividend, record date   Jul. 17, 2017  
Additional shares received by stockholders for each share held | shares   1