Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Held-to-maturity, fair value	$ 850,473	$ 552,088
Preferred stock, authorized shares	4,400,000	4,400,000
Common stock, authorized shares	350,000,000	350,000,000
Common stock, issued shares	203,085,100	204,417,093
Common stock, outstanding shares	203,085,100	204,417,093