Significant Accounting Policies Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accrued interest receivable and other assets	$ 362,260	$ 340,018
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	136,098	136,069
Other long-term borrowings, net of unamortized issuance costs	$ 99,930	99,870
Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accrued interest receivable and other assets		1,200
Junior subordinated deferrable interest debentures, net of unamortized issuance costs		1,000
Other long-term borrowings, net of unamortized issuance costs		$ 130