Deposits - Maturity Distribution of Time Certificates of Deposits (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Maturity distribution of time certificates of deposit
Three months or less	$ 1,270,823
Over three through six months	433,221
Over six through twelve months	846,327
One to two years	200,705
Two to three years	162,531
Three to four years	73,770
Four to five years	82,647
Thereafter	54
Total	3,070,078
Under $250,000
Maturity distribution of time certificates of deposit
Three months or less	213,616
Over three through six months	187,476
Over six through twelve months	420,212
One to two years	121,211
Two to three years	113,193
Three to four years	51,273
Four to five years	71,970
Thereafter	54
Total	1,179,005
$250,000 or More
Maturity distribution of time certificates of deposit
Three months or less	1,057,207
Over three through six months	245,745
Over six through twelve months	426,115
One to two years	79,494
Two to three years	49,338
Three to four years	22,497
Four to five years	10,677
Total	$ 1,891,073