Income Taxes Effective tax rate reconciliation (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Reclassification related to the Tax Act				$ 0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		$ 142,781	$ 101,033	144,760
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate		29,984	21,217	50,666
Effective Income Tax Rate Reconciliation, Tax Exempt Income		(3,949)	(3,762)	(3,384)
Affordable Housing Tax Credits and Other Tax Benefits, Amount		(3,504)	(3,826)	(1,190)
Initial impact on deferred tax liabilities from the Tax Act		0	0	(84,806)
Effective Income Tax Rate Reconciliation, Adjustment to Tax-Basis Policy Reserves, Amount		(2,460)	0	0
Effective Income Tax Rate Reconciliation, Other Adjustments		(142)	(1,979)	(1,269)
Income Tax Expense (Benefit)		$ 19,929	$ 11,650	(39,983)
AOCI Attributable to Parent
Income Tax Contingency [Line Items]
Reclassification related to the Tax Act	[1]			$ 48,226

[1] Reclassification of the initial impact of the remeasurement of deferred tax assets and liabilities upon enactment of the Tax Act. See discussion of this accounting change as discussed in Note 1.