Condensed Financial Statements of Parent Company - Condensed Statements of Income - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income:
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	$ 154,042	$ 150,375	$ 111,428
Applicable income tax benefit	(52,760)	(50,902)	(35,991)
Net income	101,282	99,473	75,437
Preferred stock dividends			1,073
Net income	101,282	99,473	74,364
Parent company
Income:
Dividends from subsidiaries	36,328	82,765	89,922
Operating income (loss)	177	38	583
Total income	36,505	82,803	90,505
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	23,817	73,920	78,479
Operating expenses	12,688	8,883	12,026
Applicable income tax benefit	4,270	2,975	3,628
Equity in undistributed earnings of subsidiary (excess distribution)	73,195	22,578	(6,670)
Net income	101,282	99,473	75,437
Preferred stock dividends			1,073
Net income	$ 101,282	$ 99,473	$ 74,364