Accumulated Other Comprehensive Loss - Schedule of Changes in Accumulated Other Comprehensive Loss After Tax (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Accumulated Other Comprehensive Income (Loss), Beginning Balance	$ (38,252)
Total other comprehensive income	4,588	3,283
Total Accumulated Other Comprehensive Income (Loss), Ending Balance	(33,664)
Unrealized Gains and Losses on Available for Sale (AFS) Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Accumulated Other Comprehensive Income (Loss), Beginning Balance	(20,855)
Other comprehensive income before reclassifications	7,216
Amounts reclassified from other comprehensive income	5
Total other comprehensive income	7,221
Total Accumulated Other Comprehensive Income (Loss), Ending Balance	(13,634)
Non-Credit Impairment Losses on AFS Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Accumulated Other Comprehensive Income (Loss), Beginning Balance	(806)
Other comprehensive income before reclassifications	142
Amounts reclassified from other comprehensive income	(115)
Total other comprehensive income	27
Total Accumulated Other Comprehensive Income (Loss), Ending Balance	(779)
Unrealized Gains and Losses on Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Accumulated Other Comprehensive Income (Loss), Beginning Balance	(6,271)
Other comprehensive income before reclassifications	(3,662)
Amounts reclassified from other comprehensive income	965
Total other comprehensive income	(2,697)
Total Accumulated Other Comprehensive Income (Loss), Ending Balance	(8,968)
Defined Benefit Pension Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Accumulated Other Comprehensive Income (Loss), Beginning Balance	(10,320)
Other comprehensive income before reclassifications	0
Amounts reclassified from other comprehensive income	37
Total other comprehensive income	37
Total Accumulated Other Comprehensive Income (Loss), Ending Balance	(10,283)
Total Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Accumulated Other Comprehensive Income (Loss), Beginning Balance	(38,252)
Other comprehensive income before reclassifications	3,696
Amounts reclassified from other comprehensive income	892
Total other comprehensive income	4,588
Total Accumulated Other Comprehensive Income (Loss), Ending Balance	$ (33,664)