Financial instruments carried at fair value, classified as a part of:

$ 5,000

$ 7,200

Fair Value, Inputs, Level 3 [Member] | Other asset-backed securities [Member]

Financial instruments carried at fair value, classified as a part of:

4,700

4,000

Fair Value, Measurements, Recurring [Member]

44,549

33,739

3,923,088

3,756,093

Fair Value, Measurements, Recurring [Member] | U.S. Treasury obligations [Member]

Assets:

213,822

205,857

Fair Value, Measurements, Recurring [Member] | U.S. Government-sponsored enterprise obligations [Member]

Assets:

56,925

56,947

Fair Value, Measurements, Recurring [Member] | State and municipal bonds [Member]

Assets:

1,253,172

1,219,979

Fair Value, Measurements, Recurring [Member] | Corporate debt, multiple observable inputs [Member]

Assets:

1,535,533

1,455,333

Fair Value, Measurements, Recurring [Member] | Private placement senior notes [Member]

Assets:

205

346

Fair Value, Measurements, Recurring [Member] | Other corporate debt, NRSRO ratings available [Member]

Assets:

10,269

13,835

Fair Value, Measurements, Recurring [Member] | Other corporate debt, NRSRO ratings not available [Member]

Assets:

885

1,010

Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities [Member]

Assets:

272,233

289,850

Fair Value, Measurements, Recurring [Member] | Agency commercial mortgage-backed securities [Member]

Assets:

44,449

59,464

Fair Value, Measurements, Recurring [Member] | Other commercial mortgage-backed securities [Member]

Assets:

70,865

74,106

Fair Value, Measurements, Recurring [Member] | Other asset-backed securities [Member]

Assets:

76,075

71,272

Fair Value, Measurements, Recurring [Member] | Financial [Member]

Assets:

80,579

70,900

Fair Value, Measurements, Recurring [Member] | Utilities/Energy [Member]

Assets:

36,798

31,383

Fair Value, Measurements, Recurring [Member] | Consumer oriented [Member]

Assets:

63,149

51,100

Fair Value, Measurements, Recurring [Member] | Technology [Member]

Assets:

17,949

11,495

Fair Value, Measurements, Recurring [Member] | Industrial [Member]

Assets:

38,241

18,200

Fair Value, Measurements, Recurring [Member] | All other [Member]

Assets:

20,116

19,540

Fair Value, Measurements, Recurring [Member] | Short-term Investments [Member]

Assets:

Financial instruments carried at fair value, classified as a part of:

87,274

71,737

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]

336,894

262,379

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury obligations [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Government-sponsored enterprise obligations [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | State and municipal bonds [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate debt, multiple observable inputs [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Private placement senior notes [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other corporate debt, NRSRO ratings available [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other corporate debt, NRSRO ratings not available [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Residential mortgage-backed securities [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Agency commercial mortgage-backed securities [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other commercial mortgage-backed securities [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other asset-backed securities [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Financial [Member]

Assets:

80,579

70,900

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Utilities/Energy [Member]

Assets:

36,798

31,383

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Consumer oriented [Member]

Assets:

63,149

51,100

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Technology [Member]

Assets:

17,949

11,495

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Industrial [Member]

Assets:

38,241

18,200

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | All other [Member]

Assets:

20,116

19,540

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member]

Assets:

Financial instruments carried at fair value, classified as a part of:

80,062

59,761

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]

3,520,582

3,433,574

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Treasury obligations [Member]

Assets:

213,822

205,857

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Government-sponsored enterprise obligations [Member]

Assets:

56,925

56,947

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | State and municipal bonds [Member]

Assets:

1,248,147

1,212,804

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate debt, multiple observable inputs [Member]

Assets:

1,535,533

1,455,333

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Private placement senior notes [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other corporate debt, NRSRO ratings available [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other corporate debt, NRSRO ratings not available [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Residential mortgage-backed securities [Member]

Assets:

272,233

289,850

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Agency commercial mortgage-backed securities [Member]

Assets:

44,449

59,464

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other commercial mortgage-backed securities [Member]

Assets:

70,865

74,106

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other asset-backed securities [Member]

Assets:

71,396

67,237

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Financial [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Utilities/Energy [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Consumer oriented [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Technology [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Industrial [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | All other [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member]

Assets:

Financial instruments carried at fair value, classified as a part of:

7,212

11,976

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

44,549

33,739

65,612

60,140

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Treasury obligations [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Government-sponsored enterprise obligations [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | State and municipal bonds [Member]

Assets:

5,025

7,175

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate debt, multiple observable inputs [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Private placement senior notes [Member]

Assets:

205

346

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other corporate debt, NRSRO ratings available [Member]

Assets:

10,269

13,835

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other corporate debt, NRSRO ratings not available [Member]

Assets:

885

1,010

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential mortgage-backed securities [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Agency commercial mortgage-backed securities [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other commercial mortgage-backed securities [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other asset-backed securities [Member]

Assets:

4,679

4,035

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Financial [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Utilities/Energy [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Consumer oriented [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Technology [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Industrial [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | All other [Member]

Assets:

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member]

Assets:

$ 0

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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