Mortgage Banking Activities, Loans Serviced for Others (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	$ 21,568,674
30 To 59 Days Past Due	279,398
60 To 89 Days Past Due	77,930
90 Days or More Past Due	71,566
Total	21,997,568
FHLMC [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	7,950,818
30 To 59 Days Past Due	52,434
60 To 89 Days Past Due	9,812
90 Days or More Past Due	25,670
Total	8,038,734
FNMA [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,922,833
30 To 59 Days Past Due	44,532
60 To 89 Days Past Due	11,233
90 Days or More Past Due	21,486
Total	7,000,084
GNMA [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,304,914
30 To 59 Days Past Due	181,669
60 To 89 Days Past Due	56,534
90 Days or More Past Due	22,471
Total	6,565,588
Other [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	390,109
30 To 59 Days Past Due	763
60 To 89 Days Past Due	351
90 Days or More Past Due	1,939
Total	$ 393,162