Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Held-to-maturity, fair value	$ 635,379	$ 609,547
Preferred stock, authorized shares	4,400,000	4,400,000
Common stock, authorized shares	350,000,000	350,000,000
Common stock, issued shares	184,895,182	184,677,696
Common stock, outstanding shares	184,895,182	184,677,696