Derivative Financial Instruments - Master Netting Arrangements (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	$ 256,480	$ 137,271
Gross Amounts offset in the Statement of Financial Position	(76)	(274)
Net Amounts of Assets Presented in the Statement of Financial Position	256,404	136,997
Gross Assets Subject To Master Netting Arrangement Not Offset	(242,658)	(117,783)
Cash Collateral Received Subject to Master Netting Arrangements	(3,756)	(7,781)
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	9,990	11,433
Gross Amounts of Recognized Liabilities	34,734	31,385
Gross Amounts offset in the Statement of Financial Position	(76)	(274)
Net Amounts of Liabilities Presented in the Statement of Financial Position	34,658	31,111
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(16,142)	(19,639)
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	18,516	11,472
Derivative
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	41,996	41,660
Gross Amounts offset in the Statement of Financial Position	(76)	(274)
Net Amounts of Assets Presented in the Statement of Financial Position	41,920	41,386
Gross Assets Subject To Master Netting Arrangement Not Offset	(28,174)	(22,172)
Cash Collateral Received Subject to Master Netting Arrangements	(3,756)	(7,781)
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	9,990	11,433
Gross Amounts of Recognized Liabilities	34,734	31,385
Gross Amounts offset in the Statement of Financial Position	(76)	(274)
Net Amounts of Liabilities Presented in the Statement of Financial Position	34,658	31,111
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(16,142)	(19,639)
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	18,516	11,472
Derivative | Interest rate swaps
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	3,485	4,609
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	3,485	4,609
Gross Assets Subject To Master Netting Arrangement Not Offset	(3,485)	(1,639)
Cash Collateral Received Subject to Master Netting Arrangements	0	(2,970)
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	0	0
Derivative | Foreign exchange forwards
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	33,025	34,004
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	33,025	34,004
Gross Assets Subject To Master Netting Arrangement Not Offset	(19,373)	(17,843)
Cash Collateral Received Subject to Master Netting Arrangements	(3,756)	(4,811)
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	9,896	11,350
Gross Amounts of Recognized Liabilities	28,693	28,136
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	28,693	28,136
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(10,329)	(16,808)
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	18,364	11,328
Derivative | Client foreign currency options
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	322	501
Gross Amounts offset in the Statement of Financial Position	(76)	(274)
Net Amounts of Assets Presented in the Statement of Financial Position	246	227
Gross Assets Subject To Master Netting Arrangement Not Offset	(152)	(144)
Cash Collateral Received Subject to Master Netting Arrangements	0	0
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	94	83
Gross Amounts of Recognized Liabilities	322	501
Gross Amounts offset in the Statement of Financial Position	(76)	(274)
Net Amounts of Liabilities Presented in the Statement of Financial Position	246	227
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(94)	(83)
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	152	144
Derivative | Client interest rate derivatives
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	5,164	2,546
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	5,164	2,546
Gross Assets Subject To Master Netting Arrangement Not Offset	(5,164)	(2,546)
Cash Collateral Received Subject to Master Netting Arrangements	0	0
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	0	0
Gross Amounts of Recognized Liabilities	5,719	2,748
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	5,719	2,748
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(5,719)	(2,748)
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	0	0
Reverse Repurchase Securities Borrowing And Similar Arrangements
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	214,484	95,611
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	214,484	95,611
Gross Assets Subject To Master Netting Arrangement Not Offset	(214,484)	(95,611)
Cash Collateral Received Subject to Master Netting Arrangements	0	0
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	0	0
Gross Amounts of Recognized Liabilities	0	0
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	0	0
Gross Liabilities Subject To Master Netting Arrangement Not Offset	0	0
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	$ 0	$ 0