Derivative Financial Instruments - Master Netting Arrangements (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	$ 378,609	$ 137,271
Gross Amounts offset in the Statement of Financial Position	(96)	(274)
Net Amounts of Assets Presented in the Statement of Financial Position	378,513	136,997
Gross Assets Subject To Master Netting Arrangement Not Offset	(367,056)	(117,783)
Cash Collateral Received Subject to Master Netting Arrangements	(2,537)	(7,781)
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	8,920	11,433
Gross Amounts of Recognized Liabilities	33,371	31,385
Gross Amounts offset in the Statement of Financial Position	(96)	(274)
Net Amounts of Liabilities Presented in the Statement of Financial Position	33,275	31,111
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(15,966)	(19,639)
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	17,309	11,472
Derivative
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	39,997	41,660
Gross Amounts offset in the Statement of Financial Position	(96)	(274)
Net Amounts of Assets Presented in the Statement of Financial Position	39,901	41,386
Gross Assets Subject To Master Netting Arrangement Not Offset	(28,444)	(22,172)
Cash Collateral Received Subject to Master Netting Arrangements	(2,537)	(7,781)
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	8,920	11,433
Gross Amounts of Recognized Liabilities	33,371	31,385
Gross Amounts offset in the Statement of Financial Position	(96)	(274)
Net Amounts of Liabilities Presented in the Statement of Financial Position	33,275	31,111
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(15,966)	(19,639)
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	17,309	11,472
Derivative | Interest rate swaps
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	3,828	4,609
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	3,828	4,609
Gross Assets Subject To Master Netting Arrangement Not Offset	(3,828)	(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	33,221	34,004
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	33,221	34,004
Gross Assets Subject To Master Netting Arrangement Not Offset	(21,778)	(17,843)
Cash Collateral Received Subject to Master Netting Arrangements	(2,537)	(4,811)
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	8,906	11,350
Gross Amounts of Recognized Liabilities	30,263	28,136
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	30,263	28,136
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(13,705)	(16,808)
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	16,558	11,328
Derivative | Client foreign currency options
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	861	501
Gross Amounts offset in the Statement of Financial Position	(96)	(274)
Net Amounts of Assets Presented in the Statement of Financial Position	765	227
Gross Assets Subject To Master Netting Arrangement Not Offset	(751)	(144)
Cash Collateral Received Subject to Master Netting Arrangements	0	0
Net Assets After Deducting Amounts Subject to Master Netting Arrangements	14	83
Gross Amounts of Recognized Liabilities	861	501
Gross Amounts offset in the Statement of Financial Position	(96)	(274)
Net Amounts of Liabilities Presented in the Statement of Financial Position	765	227
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(14)	(83)
Cash Collateral Pledged Subject to Master Netting Arrangements	0	0
Net Liabilities After Deducting Amounts Subject to Master Netting Arrangements	751	144
Derivative | Client interest rate derivatives
Assets and Liabilities Subject to Master Netting Arrangements [Line Items]
Gross Amounts of Recognized Assets	2,087	2,546
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	2,087	2,546
Gross Assets Subject To Master Netting Arrangement Not Offset	(2,087)	(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	2,247	2,748
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	2,247	2,748
Gross Liabilities Subject To Master Netting Arrangement Not Offset	(2,247)	(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	338,612	95,611
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	338,612	95,611
Gross Assets Subject To Master Netting Arrangement Not Offset	(338,612)	(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