Debt And Shareholders' Equity JUNIOR SUBORDINATED NOTES (Details) $ in Millions	3 Months Ended
	Sep. 30, 2016 USD ($)
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 129
AMEGY STATUTORY TRUST ONE [Member]
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 51
Coupon Rate	3mL+2.85%
Debt Instrument, Date of First Required Payment	Sep. 17, 2016
AMEGY STATUTORY TRUSTS 3 [Member] [Member]
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 62
Coupon Rate	3mL+1.78%
Debt Instrument, Date of First Required Payment	Sep. 15, 2016
STOCKMEN S STATUTORY TRUST 2 [Member]
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 8
Coupon Rate	3mL+3.15%
Debt Instrument, Date of First Required Payment	Sep. 26, 2016
STOCKMEN S STATUTORY TRUST 3 [Member]
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 8
Coupon Rate	3mL+2.89%
Debt Instrument, Date of First Required Payment	Sep. 17, 2016