Deposits (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Deposits [Abstract]
FDIC Deposit Insurance Limit	$ 250,000
Time Deposits Greater than $250,000, Carrying Value	578,100,000	$ 552,300,000
Deposits, by Type [Abstract]
Demand	9,274,470,000	8,086,784,000
Checking With Interest	4,445,353,000	4,091,333,000
Money market accounts	8,205,705,000	8,264,811,000
Savings	1,909,021,000	1,728,504,000
Time	3,096,206,000	3,507,145,000
Total deposits	26,930,755,000	$ 25,678,577,000
Maturities of Time Deposits [Abstract]
2014	2,359,710,000
2015	453,560,000
2016	114,448,000
2017	111,857,000
2018	56,631,000
Thereafter	$ 0