Parent Company Condensed Financial Information - Statements of Cash Flows (Details) - USD ($) $ in Thousands		12 Months Ended
	Sep. 11, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES
Net Income		$ 105,334	$ 72,968	$ 71,392
Net Cash Provided by Operating Activities		128,017	114,236	96,805
INVESTING ACTIVITIES
Net Cash Used in Investing Activities		(201,964)	(212,415)	(616,653)
FINANCING ACTIVITIES
Sale of treasury shares, net		(657)	(689)	(115)
Purchase of treasury shares		12,256	0	0
Cash dividends paid to common shareholders		(34,539)	(28,569)	(26,784)
Payment to repurchase of warrant	$ (7,700)	(7,652)	0	0
Net Cash Provided by Financing Activities		112,284	75,845	559,935
Net increase (decrease) in cash and cash equivalents		38,337	(22,334)	40,087
Cash and cash equivalents at beginning of year		117,152	139,486	99,399
Cash and Cash Equivalents at End of Year		155,489	117,152	139,486
Parent Company
OPERATING ACTIVITIES
Net Income		105,334	72,968	71,392
Equity in undistributed (earnings) losses of subsidiaries		(64,366)	(39,937)	(40,410)
Tax benefit from stock-based compensation		0	0	(9)
Other		1,695	480	379
Net Cash Provided by Operating Activities		42,663	33,511	31,352
INVESTING ACTIVITIES
Net investments in subsidiaries		0	0	0
Net Cash Used in Investing Activities		0	0	0
FINANCING ACTIVITIES
Sale of treasury shares, net		(657)	(689)	(115)
Purchase of treasury shares		12,256	0	0
Cash dividends paid to common shareholders		(34,539)	(28,569)	(26,784)
Tax benefit from stock-based compensation		0	0	9
Payment to repurchase of warrant		(7,652)	0	0
Net Cash Provided by Financing Activities		(55,104)	(29,258)	(26,890)
Net increase (decrease) in cash and cash equivalents		(12,441)	4,253	4,462
Cash and cash equivalents at beginning of year		21,310	17,057	12,595
Cash and Cash Equivalents at End of Year		$ 8,869	$ 21,310	$ 17,057