Significant Accounting Policies Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accrued interest receivable and other assets	$ 308,347	$ 340,018
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	136,083	136,069
Other long-term borrowings, net of unamortized issuance costs	$ 99,900	99,870
Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accrued interest receivable and other assets		(1,176)
Junior subordinated deferrable interest debentures, net of unamortized issuance costs		(1,046)
Other long-term borrowings, net of unamortized issuance costs		$ (130)