Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 22,451	$ 35,630	$ 86,430	$ 93,715
Unrealized gains (losses) on securities:
Change in unrealized holding gains (losses), net	46,166	(24,213)	33,289	59,156
Less: Reclassifications adjustment for gains included in net income	(101)	(26)	(8,404)	(4,065)
Change in unrealized gains (losses) on securities during the period	46,065	(24,239)	24,885	55,091
Income tax (expense) benefit	(17,394)	9,165	(9,361)	(20,624)
Other comprehensive income (loss)	28,671	(15,074)	15,524	34,467
Comprehensive income	$ 51,122	$ 20,556	$ 101,954	$ 128,182