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Condensed Financial Information (Parent Company Only) - Condensed Balance Sheets (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | --- | --- | ---
Condensed balance sheets: |  |  |  |
Cash and cash equivalents | $ 758,986 | $ 782,023 |  |
Investment in subsidiaries, at equity: |  |  |  |
Other assets | 145,747 | 81,705 |  |
Total assets | 12,213,255 | 9,063,895 |  |
Subordinated debentures held by subsidiary trusts | 82,477 | 82,477 |  |
Total liabilities | 10,785,639 | 8,081,302 |  |
Stockholders’ equity | 1,427,616 | 982,593 | $ 950,493 | $ 908,924
Total liabilities and stockholders’ equity | 12,213,255 | 9,063,895 |  |
Parent Company |  |  |  |
Condensed balance sheets: |  |  |  |
Cash and cash equivalents | 42,300 | 138,400 |  |
Investment in subsidiaries, at equity: |  |  |  |
Equity method investments | 1,432,300 | 932,000 |  |
Advances from subsidiaries, net | 25,700 | 0 |  |
Other assets | 61,700 | 35,400 |  |
Total assets | 1,562,000 | 1,105,800 |  |
Other liabilities | 51,900 | 18,000 |  |
Advances from subsidiaries, net | 0 | 2,700 |  |
Long-term debt | 0 | 20,000 |  |
Subordinated debentures held by subsidiary trusts | 82,500 | 82,500 |  |
Total liabilities | 134,400 | 123,200 |  |
Stockholders’ equity | 1,427,600 | 982,600 |  |
Total liabilities and stockholders’ equity | 1,562,000 | 1,105,800 |  |
Bank subsidiary | Parent Company |  |  |  |
Investment in subsidiaries, at equity: |  |  |  |
Equity method investments | $ 1,432,300 | $ 932,000 |  |

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