Mortgage Banking Activities Mortgage Banking Activities, Loans Serviced for Others (Details) $ in Thousands	Sep. 30, 2015 USD ($)
Financing Receivable, Recorded Investment, Aging [Abstract]
Mortgage Loans Serviced For Others, Current	$ 18,588,516
Mortgage Loans Serviced For Others, 30 To 59 Days Past Due	220,144
Mortgage Loans Serviced For Others, 60 To 89 Days Past Due	54,372
Mortgage Loans Serviced For Others, Greater Than 90 Days or More Past Due	65,694
Mortgage Loans Serviced For Others	18,928,726
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Mortgage Loans Serviced For Others, Current	6,177,382
Mortgage Loans Serviced For Others, 30 To 59 Days Past Due	36,398
Mortgage Loans Serviced For Others, 60 To 89 Days Past Due	7,426
Mortgage Loans Serviced For Others, Greater Than 90 Days or More Past Due	26,517
Mortgage Loans Serviced For Others	6,247,723
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Mortgage Loans Serviced For Others, Current	6,428,098
Mortgage Loans Serviced For Others, 30 To 59 Days Past Due	32,897
Mortgage Loans Serviced For Others, 60 To 89 Days Past Due	7,009
Mortgage Loans Serviced For Others, Greater Than 90 Days or More Past Due	19,297
Mortgage Loans Serviced For Others	6,487,301
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Mortgage Loans Serviced For Others, Current	5,483,012
Mortgage Loans Serviced For Others, 30 To 59 Days Past Due	145,747
Mortgage Loans Serviced For Others, 60 To 89 Days Past Due	38,984
Mortgage Loans Serviced For Others, Greater Than 90 Days or More Past Due	15,816
Mortgage Loans Serviced For Others	5,683,559
Other Investor Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Mortgage Loans Serviced For Others, Current	500,024
Mortgage Loans Serviced For Others, 30 To 59 Days Past Due	5,102
Mortgage Loans Serviced For Others, 60 To 89 Days Past Due	953
Mortgage Loans Serviced For Others, Greater Than 90 Days or More Past Due	4,064
Mortgage Loans Serviced For Others	$ 510,143