Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidated Statements of Comprehensive Income
Net income	$ 284,392	$ 264,394	$ 183,682
Other comprehensive income (loss), net of tax:
Net change in pensions and other benefits	297	2,960	4,291
Net change in investment securities	100,149	(14,259)	(14,159)
Net change in cash flow derivative hedges		(4,445)	1,496
Other comprehensive income (loss)	100,446	(15,744)	(8,372)
Total comprehensive income	$ 384,838	$ 248,650	$ 175,310