Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Held-to-maturity, fair value	$ 602,355	$ 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	203,192,991	203,014,903
Common stock, outstanding shares	203,192,991	203,014,903