Investment Securities (Continuous Unrealized Loss Position) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014 securities	Dec. 31, 2013 securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	$ 175,453	$ 232,060
Less than 12 months, gross unrealized losses	9,538	17,408
12 months or more, estimated fair value	155,290	97,940
12 months or more, gross unrealized losses	11,534	9,083
Total, estimated fair value	330,743	330,000
Total, gross unrealized losses	21,072	26,491
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	141,002	141,125
Less than 12 months, gross unrealized losses	8,058	10,670
12 months or more, estimated fair value	0	0
12 months or more, gross unrealized losses	0	0
Total, estimated fair value	141,002	141,125
Total, gross unrealized losses	8,058	10,670
Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	316,455	373,185
Less than 12 months, gross unrealized losses	17,596	28,078
12 months or more, estimated fair value	155,290	97,940
12 months or more, gross unrealized losses	11,534	9,083
Total, estimated fair value	471,745	471,125
Total, gross unrealized losses	29,130	37,161
12 months or more, number of securities	14	10
Residential mortgage-backed securities - GSE [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	164,313	222,475
Less than 12 months, gross unrealized losses	8,975	16,585
12 months or more, estimated fair value	133,699	76,501
12 months or more, gross unrealized losses	10,454	7,755
Total, estimated fair value	298,012	298,976
Total, gross unrealized losses	19,429	24,340
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	131,427	131,817
Less than 12 months, gross unrealized losses	7,564	9,907
12 months or more, estimated fair value	0	0
12 months or more, gross unrealized losses	0	0
Total, estimated fair value	131,427	131,817
Total, gross unrealized losses	7,564	9,907
Residential mortgage-backed securities - Private [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	1,297
Less than 12 months, gross unrealized losses	9
12 months or more, estimated fair value	0
12 months or more, gross unrealized losses	0
Total, estimated fair value	1,297
Total, gross unrealized losses	9
Commercial mortgage-backed securities - GSE [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	0	0
Less than 12 months, gross unrealized losses	0	0
12 months or more, estimated fair value	21,591	21,439
12 months or more, gross unrealized losses	1,080	1,328
Total, estimated fair value	21,591	21,439
Total, gross unrealized losses	1,080	1,328
Commercial mortgage-backed securities - Private [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value		9,585
Less than 12 months, gross unrealized losses		823
12 months or more, estimated fair value		0
12 months or more, gross unrealized losses		0
Total, estimated fair value		9,585
Total, gross unrealized losses		823
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	9,575	9,308
Less than 12 months, gross unrealized losses	494	763
12 months or more, estimated fair value	0	0
12 months or more, gross unrealized losses	0	0
Total, estimated fair value	9,575	9,308
Total, gross unrealized losses	494	763
Corporate notes [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	9,843
Less than 12 months, gross unrealized losses	554
12 months or more, estimated fair value	0
12 months or more, gross unrealized losses	0
Total, estimated fair value	9,843
Total, gross unrealized losses	$ 554