Mortgage Banking Activities Mortgage Banking Activities, Loans Serviced for Others (Details) $ in Thousands	Jun. 30, 2018 USD ($)
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	$ 21,483,016
30 to 59 Days Past Due	350,261
60 to 89 Days Past Due	66,535
90 Days or More Past Due	63,497
Total	21,963,309
FHLMC [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	7,932,832
30 to 59 Days Past Due	68,996
60 to 89 Days Past Due	9,405
90 Days or More Past Due	25,129
Total	8,036,362
FNMA [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,491,492
30 to 59 Days Past Due	77,424
60 to 89 Days Past Due	9,118
90 Days or More Past Due	20,918
Total	6,598,952
GNMA [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,624,862
30 to 59 Days Past Due	198,852
60 to 89 Days Past Due	47,791
90 Days or More Past Due	15,204
Total	6,886,709
Other [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	433,830
30 to 59 Days Past Due	4,989
60 to 89 Days Past Due	221
90 Days or More Past Due	2,246
Total	$ 441,286