Short-term borrowings (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of Short-term Debt

The detail of short-term borrowings for the years 2017, 2016 and 2015 is presented in the following table:

(Dollars in thousands)	Federal Funds Purchased			Securities Sold Under Agreements to Repurchase			Trading Liabilities			Other Short-term Borrowings
2017
Average balance	$	447,137		$	578,666		$	685,891		$	554,502
Year-end balance	399,820			656,602			638,515			2,626,213
Maximum month-end outstanding	568,490			743,684			896,943			2,626,213
Average rate for the year	1.06		%	0.72		%	2.26		%	1.28		%
Average rate at year-end	1.48			0.64			2.22			1.44
2016
Average balance	$	589,223		$	425,452		$	771,039		$	198,440
Year-end balance	414,207			453,053			561,848			83,177
Maximum month-end outstanding	695,083			528,024			874,076			792,736
Average rate for the year	0.52		%	0.08		%	1.95		%	0.67		%
Average rate at year-end	0.73			0.08			2.46			0.96
2015
Average balance	$	705,054		$	370,097		$	733,189		$	164,951
Year-end balance	464,166			338,133			566,019			137,861
Maximum month-end outstanding	1,228,125			524,191			866,005			339,468
Average rate for the year	0.26		%	0.06		%	2.18		%	0.67		%
Average rate at year-end	0.50			0.09			2.41			0.82