Comprehensive Income/Loss (Details2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest on borrowings expense	$ 44,862		$ 41,853
Tax (expense) benefit	(4,114)		(4,621)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	837
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Loss on Cash Flow Hedge [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	1,414
Tax (expense) benefit	(578)
Net of tax	836
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Loss on Cash Flow Hedge [Member] | Interest Rate Contract [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest on borrowings expense	1,414
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined Benefit Pension Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior Service costs	22	[1]
Tax (expense) benefit	(21)
Net of tax	$ 1

[1] The amortization of prior service costs is included in the computation of net periodic pension cost as disclosed in the Employee Benefit Plans footnote in the Company's Annual Report on Form 10-K for the year ended December 31, 2012, filed with the Securities and Exchange Commission.