Parent Company Only Condensed Financial Statements - Consolidated Statements of Cash Flow (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation	$ 4,032	$ 3,452	$ 3,427
Net cash provided by operating activities	92,457	108,808	45,791
Cash flows from investing activities:
Net cash paid for acquisitions and dispositions	(23,377)	0	4,456
Net cash used in investing activities	(378,520)	(331,618)	(312,444)
Cash flows from financing activities:
Proceeds from Notes Payable	41,000	2,000	10,000
Repayments of Notes Payable	8,714	0	10,000
Cash dividends paid	(16,568)	(10,845)	(10,249)
Payments for Repurchase of Common Stock	15,526	19,387	16,636
Net cash provided by financing activities	256,767	266,039	221,174
Net (decrease) increase in cash and cash equivalents	(29,296)	43,229	(45,479)
Cash and cash equivalents, beginning of period	196,552	153,323	198,802
Cash and cash equivalents, end of period	$ 167,256	$ 196,552	$ 153,323
Noncash transactions:
Stock Issued During Period, Shares, Acquisitions	171,885	0	141,729
Parent [Member]
Cash flows from operating activities:
Net income available to common shareholders	$ 92,739	$ 89,217	$ 48,190
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation	4,032	3,452	3,427
Net income of subsidiaries	(104,223)	(94,898)	(55,053)
Dividends from subsidiaries	61,500	31,200	20,000
Other, net	(1,063)	(953)	(1,806)
Net cash provided by operating activities	52,985	28,018	14,758
Cash flows from investing activities:
Net cash paid for acquisitions and dispositions	(36,015)	0	(25,187)
Purchases of other investments	(2,634)	(2,729)	(3,679)
Proceeds from distributions on other investments	1,271	1,911	1,634
Net cash used in investing activities	(37,378)	(818)	(27,232)
Cash flows from financing activities:
Proceeds from Notes Payable	1,000	2,000	10,000
Repayments of Notes Payable	3,000	0	10,000
Cash dividends paid	(16,569)	(10,845)	(10,249)
Payments for Repurchase of Common Stock	15,526	19,387	16,636
Payments for the repurchase of equity instruments, net	(212)	(2,576)	(2,909)
Net cash provided by financing activities	(21)	(30,808)	(29,794)
Net (decrease) increase in cash and cash equivalents	15,586	(3,608)	(42,268)
Cash and cash equivalents, beginning of period	6,369	9,977	52,245
Cash and cash equivalents, end of period	$ 21,955	$ 6,369	$ 9,977
Noncash transactions:
Stock Issued During Period, Shares, Acquisitions	171,885	0	141,729
Proceeds from Issuance of Long-term Debt	$ 40,000	$ 0	$ 0
Repayments of Long-term Debt	$ (5,714)	$ 0	$ 0