Bank Deposits (Scheduled Maturities of Certificates of Deposit) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deposits Liabilities Balance Sheet Reported Amounts [Abstract]
Within one year	$ 27,440	$ 438
One to three years	38,550	148
Three to five years	15,511
Certificates of deposit, less than $100,000	81,501	586
Within one year	1,513,202	651
One to three years	157,232	338
Three to five years	11,401
Certificates of deposit, $100,000 and greater	1,681,835	989
Total certificates of deposit	$ 1,763,336	$ 1,575