Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Held-to-maturity, fair value	$ 553,088	$ 677,196
Preferred stock, authorized shares	4,400,000	4,400,000
Common stock, authorized shares	350,000,000	350,000,000
Common stock, issued shares	204,278,594	203,014,903
Common stock, outstanding shares	204,278,594	203,014,903