Investments (Unrealized Losses) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Jun. 30, 2011
Investment securities available for sale:
Less than 12 months, fair value	$ 1,639,404	$ 648,869
12 months or more, fair value	1,678	2,026
Total fair value	1,641,082	650,895
Less than 12 months, unrealized losses	1,529	1,592
12 months or more, unrealized losses	37	50
Total unrealized losses	1,566	1,642
U. S. Treasury
Investment securities available for sale:
Less than 12 months, fair value	528,579	50,307
12 months or more, fair value	0	0
Total fair value	528,579	50,307
Less than 12 months, unrealized losses	156	5
12 months or more, unrealized losses	0	0
Total unrealized losses	156	5
Government Agency
Investment securities available for sale:
Less than 12 months, fair value	818,772	507,210
12 months or more, fair value	0	0
Total fair value	818,772	507,210
Less than 12 months, unrealized losses	565	1,140
12 months or more, unrealized losses	0	0
Total unrealized losses	565	1,140
Corporate Bonds
Investment securities available for sale:
Less than 12 months, fair value		9,957
12 months or more, fair value		0
Total fair value		9,957
Less than 12 months, unrealized losses		43
12 months or more, unrealized losses		0
Total unrealized losses		43
Residential Mortgage-Backed Securities
Investment securities available for sale:
Less than 12 months, fair value	292,053	80,866
12 months or more, fair value	1,668	2,016
Total fair value	293,721	82,882
Less than 12 months, unrealized losses	808	401
12 months or more, unrealized losses	37	50
Total unrealized losses	845	451
Investment securities held to maturity:
Less than 12 months, fair value	0	0
Less than 12 months, unrealized losses	0	0
12 months or more, fair value	19	29
12 months or more, unrealized losses	27	26
Total fair value	19	29
Total unrealized losses	27	26
State, County and Municipal
Investment securities available for sale:
Less than 12 months, fair value	0	529
12 months or more, fair value	10	10
Total fair value	10	539
Less than 12 months, unrealized losses	0	3
12 months or more, unrealized losses	0	0
Total unrealized losses	$ 0	$ 3