Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Held-to-maturity, fair value	$ 608,531	$ 512,705
Preferred stock, no par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized	100,000,000	60,000,000
Common stock, shares issued	70,599,133	38,167,861
Common stock, shares outstanding	70,599,133	38,167,861