Derivatives and Hedging - Netting Arrangements (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Derivative financial assets:
Derivative assets, total derivatives subject to a master netting arrangement, gross amounts recognized		$ 106,289	$ 93,409
Derivative assets, total derivative subject to a master netting arrangement, gross amounts offset in the condensed consolidated balance sheet		0	0
Derivative assets, total derivatives subject to a master netting arrangement, net amount presented in the condensed consolidated balance sheets		106,289	93,409
Derivative assets, total derivatives subject to a master netting arrangement, financial instruments collateral received/pledged	[1]	0	0
Derivate assets, total derivatives subject to a master netting arrangement, cash collateral received/pledged	[1]	34,430	21,423
Derivative asset, total derivatives subject to a master netting arrangement, net amount		71,859	71,986
Derivative assets, total derivatives not subject to a master netting arrangement		72,480	114,685
Derivative assets, total derivatives not subject to a master netting arrangement, net amount		72,480	114,685
Total derivative financial assets, gross amounts recognized		178,769	208,094
Total derivative financial assets, net amount presented in the condensed consolidated balance sheet		178,769	208,094
Total derivative financial assets, net amount		144,339	186,671
Derivative financial liabilities:
Derivative liabilities, total derivative subject to a master netting arrangement, gross amounts recognized		96,522	108,955
Derivative liabilities, total derivative subject to a master netting arrangement, gross amount offset in the condensed consolidated balance sheets		0	0
Derivative liabilities, total derivative subject to a master netting arrangement, net amount presented in the condensed consolidated balance sheets		96,522	108,955
Derivative liabilities, total derivatives subject to a master netting arrangement, financial instruments collateral received/pledged	[1]	1,782	4,545
Derivative liabilities, total derivative subject to a master netting arrangement, cash collateral received/pledged	[1]	80,045	92,396
Derivate liabilities, total derivatives subject to master netting arrangement, net amount		14,695	12,014
Derivative liabilities, total derivatives not subject to a master netting arrangement		153,904	98,977
Derivative liabilities, total derivatives not subject to a master netting arrangement, net amount		153,904	98,977
Derivative liabilities, total derivative financial liabilities, gross amount recognized		250,426	207,932
Total derivative financial liabilities, net amount presented in the condensed consolidated balance sheets		250,426	207,932
Total derivative financial liabilities, net amount		$ 168,599	$ 110,991

[1] The actual amount of collateral received/pledged is limited to the asset/liability balance and does not include excess collateral received/pledged. When excess collateral exists, the collateral shown in the table above has been allocated based on the percentage of the actual amount of collateral posted.