Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Amortized cost	$ 1,850,723	$ 2,078,131
Fair Value, Held-to-maturity	$ 726,755	$ 819,215
Common stock, par value
Common stock, authorized	225,000,000	225,000,000
Common stock, shares issued	140,334,671	110,184,922
Common stock, shares outstanding	140,334,671	110,184,922

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Face amount per share of no-par value common stock.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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