Investments Investments (Available for Sale) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 699,641	$ 514,237
Gross Unrealized Holding Gains	18,495	2,882
Gross Unrealized Holding Losses	1,497	6,868
Estimated Fair Value	716,639	510,251
U.S. Treasury securities and obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	110	610
Gross Unrealized Holding Gains	2	2
Gross Unrealized Holding Losses	0	1
Estimated Fair Value	112	611
Obligations of states, municipalities and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	145,834	153,884
Gross Unrealized Holding Gains	7,990	2,010
Gross Unrealized Holding Losses	189	1,294
Estimated Fair Value	153,635	154,600
Corporate and other securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	177,927	97,889
Gross Unrealized Holding Gains	4,631	264
Gross Unrealized Holding Losses	194	1,401
Estimated Fair Value	182,364	96,752
Commercial mortgage and asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	190,472	151,137
Gross Unrealized Holding Gains	3,912	252
Gross Unrealized Holding Losses	478	1,522
Estimated Fair Value	193,906	149,867
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	185,298	110,717
Gross Unrealized Holding Gains	1,960	354
Gross Unrealized Holding Losses	636	2,650
Estimated Fair Value	$ 186,622	$ 108,421

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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