Consolidated Statements Of Comprehensive Income (Parenthetical) (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other comprehensive income/(loss), tax	$ 4,400,000	$ (2,100,000)	$ 18,100,000	$ (10,400,000)
Reclassifications to earnings of realized losses on available-for-sale securities		0	200,000	0
Increase in accumulated comprehensive income	17,900,000		17,900,000
Reclassifications to earnings of gains on cash flow hedging instruments	600,000	$ 1,500,000	2,900,000	$ 3,300,000
ASU 2019-04 [Member]
Increase in accumulated comprehensive income	$ 17,900,000
ASU 2018-02 [Member]
Reclassification to retained earnings related to cash flow hedges and investment portfolio risk			$ 3,000,000.0