Mortgage Banking (Details) (USD $)	1 Months Ended	9 Months Ended
	Nov. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Mortgage Banking [Abstract]
Period of put back response		60 days
Residential mortgage loans sold		$ 671,200,000	$ 1,132,000,000
Gains on sales of residential mortgage loans, before tax		7,900,000	24,200,000
Mortgage loans serviced for others		5,586,000,000		5,461,000,000
Mortgage servicing rights [Abstract]
Balance at beginning of period		67,834,000	47,341,000
Origination of servicing assets		8,884,000	15,551,000
Change in fair value [Abstract]
Due to market changes		(3,060,000)	7,881,000
Due to runoff		(6,568,000)	(7,623,000)
Balance at end of period		67,090,000	63,150,000
Mortgage Loans on Real Estate [Line Items]
Total mortgage loans sold and serviced for others		5,585,773,000		5,461,676,000
Schedule of changes in the reserve for mortgage loan [Abstract]
Balance at beginning of period		1,050,000	7,800,000
Provision for putback expenses		450,000	1,050,000
Losses		(403,000)	(3,867,000)
Balance at end of period		1,097,000	4,983,000
Mortgage loan servicing representation and warranty expenses		450,000	1,000,000
Payments to FNMA for repurchase obligations	3,600,000
Federal National Mortgage Association [Member]
Mortgage Loans on Real Estate [Line Items]
Total mortgage loans sold and serviced for others		3,556,490,000		3,499,659,000
Government National Mortgage Association [Member]
Mortgage Loans on Real Estate [Line Items]
Total mortgage loans sold and serviced for others		1,916,010,000		1,830,420,000
Federal Home Loan Mortgage Corporation [Member]
Mortgage Loans on Real Estate [Line Items]
Total mortgage loans sold and serviced for others		83,250,000		92,599,000
Other [Member]
Mortgage Loans on Real Estate [Line Items]
Total mortgage loans sold and serviced for others		$ 30,023,000		$ 38,998,000