CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 57,486	$ 58,069	$ 54,958
Other comprehensive (loss) income:
Change in unrealized (depreciation) appreciation of available-for-sale securities	(4,562)	5,488	(20,915)
Reclassification adjustment for realized (gains) losses included in net income	(4)	(963)	168
Income tax effect	1,714	(1,699)	7,789
Other comprehensive (loss) income, net of tax	(2,852)	2,826	(12,958)
Comprehensive income	$ 54,634	$ 60,895	$ 42,000