Mortgage Banking Activities, Loans Serviced for Others (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	$ 21,188,078
30 To 59 Days Past Due	326,636
60 To 89 Days Past Due	79,657
90 Days or More Past Due	63,964
Total	21,658,335
FHLMC [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	7,798,790
30 To 59 Days Past Due	58,271
60 To 89 Days Past Due	11,139
90 Days or More Past Due	25,239
Total	7,893,439
FNMA [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,458,561
30 To 59 Days Past Due	63,321
60 To 89 Days Past Due	12,413
90 Days or More Past Due	20,858
Total	6,555,153
GNMA [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,568,459
30 To 59 Days Past Due	200,747
60 To 89 Days Past Due	56,024
90 Days or More Past Due	15,996
Total	6,841,226
Other [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	362,268
30 To 59 Days Past Due	4,297
60 To 89 Days Past Due	81
90 Days or More Past Due	1,871
Total	$ 368,517