Deposits - Maturity Distribution of Time Certificates of Deposits (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Maturity distribution of time certificates of deposit
Three months or less	$ 790,231
Over three through six months	835,371
Over six through twelve months	595,012
One to two years	169,638
Two to three years	173,830
Three to four years	64,513
Four to five years	78,964
Thereafter	34
Total	2,707,593
Under $250,000
Maturity distribution of time certificates of deposit
Three months or less	241,794
Over three through six months	219,641
Over six through twelve months	353,128
One to two years	110,732
Two to three years	117,527
Three to four years	51,400
Four to five years	69,740
Thereafter	34
Total	1,163,996
$250,000 or More
Maturity distribution of time certificates of deposit
Three months or less	548,437
Over three through six months	615,730
Over six through twelve months	241,884
One to two years	58,906
Two to three years	56,303
Three to four years	13,113
Four to five years	9,224
Total	$ 1,543,597