Condensed Financial Information (Parent Company Only) (Cash flows) (Details) - USD ($) $ in Thousands		12 Months Ended
	Nov. 02, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income		$ 77,329	$ 62,874	$ 54,684
Net cash provided by (used in) operating activities		(1,257,003)	204,335	(175,886)
Investing Activities
Other investing activities		126	74	189
Net cash used in investing activities		(957,675)	(509,066)	(523,137)
Financing Activities
Dividends paid		(17,254)	(10,216)	(7,950)
Proceeds from issuance of common stock	$ 106,200			106,245
Proceeds from issuance of preferred stock		192,915
Repurchase of preferred stock		(21,850)
Net cash provided by financing activities		2,384,863	281,736	612,841
Net Change in Cash and Cash Equivalents		170,185	(22,995)	(86,182)
Cash and Cash Equivalents, Beginning of Period		336,524	359,519	445,701
Cash and Cash Equivalents, End of Period		506,709	336,524	359,519
Reportable Legal Entities | Company
Operating Activities
Net income		77,329	62,874	54,684
Adjustments to reconcile net income to net cash used in operating activities		(36,567)	(30,522)	(44,185)
Net cash provided by (used in) operating activities		40,762	32,352	10,499
Investing Activities
Return of capital from/(contributed capital to) subsidiaries		(173,078)	19,368	(101,868)
Net cash paid for acquisitions			(27,209)
Other investing activities		126	74	189
Net cash used in investing activities		(172,952)	(7,767)	(101,679)
Financing Activities
Net change in short-term subordinated debt		23,382	19,418
Dividends paid		(17,254)	(10,216)	(7,950)
Proceeds from issuance of common stock				106,245
Proceeds from issuance of preferred stock		(192,915)
Repurchase of preferred stock		(21,850)
Net cash provided by financing activities		130,429	(29,634)	98,295
Net Change in Cash and Cash Equivalents		(1,761)	(5,049)	7,115
Cash and Cash Equivalents, Beginning of Period		2,224	7,273	158
Cash and Cash Equivalents, End of Period		$ 463	$ 2,224	$ 7,273