The aggregate amount of time deposits in denominations of more than $250 thousand at December 31, 2018 and 2017, was $1.77 billion and $1.28 billion, respectively. Included in time deposits of more than $250 thousand were $300.0 million in California State Treasurer’s deposits at December 31, 2018 and 2017. The California State Treasurer’s deposits are subject to withdrawal based on the State’s periodic evaluations. The Company is required to pledge eligible collateral of at least 110% of outstanding deposits. At December 31, 2018 and 2017, securities with carrying values of approximately $336.8 million and $337.7 million, respectively, were pledged as collateral for the California State Treasurer’s deposits.

The Company also utilizes brokered deposits as a secondary source of funds. Total brokered deposits at December 31, 2018 and December 31, 2017, totaled $1.57 billion and $797.0 million, respectively. Brokered deposits at December 31, 2018 consisted of $370.4 million in brokered money market and NOW accounts and $1.20 billion in brokered time deposits accounts. Brokered deposits at December 31, 2017 consisted of $258.5 million in brokered money market and NOW accounts and $538.5 million in brokered time deposits accounts.

At December 31, 2018, the scheduled maturities for time deposits were as follows:



	December 31, 2018
	(Dollars in thousands)
Scheduled maturities in:
2019	$	5,183,279
2020	635,279
2021	31,059
2022	1,828
2023 and thereafter	19,179
Total	$	5,870,624

The following table presents the maturity schedules of time deposits in amounts of more than $250 thousand as of December 31, 2018:



	More than $250,000
	(Dollars in thousands)
Three months or less	$	571,535
Over three months through six months	332,352
Over six months through twelve months	774,224
Over twelve months	95,319
Total	$	1,773,430

Interest expense on deposits for the periods indicated is summarized as follows:



	Year Ended December 31,
	2018		2017		2016
	(Dollars in thousands)
Money market and NOW	$	43,252	$	31,856	$	21,136
Savings deposits	1,889		1,354		1,282
Time deposits	89,817		41,692		25,673
Total deposit interest expense	$	134,958	$	74,902	$	48,091