Interim Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Available-for-sale securities, cost	$ 12,514,893	$ 16,375,941
Held-to-maturity securities	$ 7,885,333	$ 8,758,622
Preferred stock, par value, in usd per share	$ 0.001	$ 0.001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value, in usd per share	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares outstanding	52,061,435	51,610,226