Bank Deposits (Scheduled Maturities of Certificates of Deposit) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Deposits Liabilities Balance Sheet Reported Amounts [Abstract]
Within one year	$ 5,317	$ 4,858
One to three years	437	623
Three to five years	113	140
Certificates of deposit, less than $100,000	5,867	5,621
Within one year	706,225	1,535,784
One to three years	70,398	195,159
Three to five years	10,025	26,772
Certificates of deposit, $100,000 and greater	786,648	1,757,715
Total certificates of deposit	$ 792,515	$ 1,763,336