Investment Securities (Continuous Unrealized Loss Position) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	$ 135,012	$ 1,154
Less than 12 months, gross unrealized losses	657	4
12 months or more, estimated fair value	145,265	277,630
12 months or more, gross unrealized losses	3,245	6,162
Total, estimated fair value	280,277	278,784
Total, gross unrealized losses	3,902	6,166
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	34,426	0
Less than 12 months, gross unrealized losses	80	0
12 months or more, estimated fair value	39,603	122,876
12 months or more, gross unrealized losses	292	1,702
Total, estimated fair value	74,029	122,876
Total, gross unrealized losses	372	1,702
Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	169,438	1,154
Less than 12 months, gross unrealized losses	737	4
12 months or more, estimated fair value	184,868	400,506
12 months or more, gross unrealized losses	3,537	7,864
Total, estimated fair value	354,306	401,660
Total, gross unrealized losses	4,274	7,868
Residential mortgage-backed securities - GSE [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	80,677	0
Less than 12 months, gross unrealized losses	557	0
12 months or more, estimated fair value	145,265	245,457
12 months or more, gross unrealized losses	3,245	5,593
Total, estimated fair value	225,942	245,457
Total, gross unrealized losses	3,802	5,593
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	34,426	0
Less than 12 months, gross unrealized losses	80	0
12 months or more, estimated fair value	39,603	112,878
12 months or more, gross unrealized losses	292	1,635
Total, estimated fair value	74,029	112,878
Total, gross unrealized losses	372	1,635
Residential mortgage-backed securities - Private [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	1,135	1,154
Less than 12 months, gross unrealized losses	4	4
12 months or more, estimated fair value	0	0
12 months or more, gross unrealized losses	0	0
Total, estimated fair value	1,135	1,154
Total, gross unrealized losses	4	4
Commercial mortgage-backed securities - GSE [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	22,208	0
Less than 12 months, gross unrealized losses	71	0
12 months or more, estimated fair value	0	21,958
12 months or more, gross unrealized losses	0	419
Total, estimated fair value	22,208	21,958
Total, gross unrealized losses	71	419
Commercial mortgage-backed securities - Private [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value		0
Less than 12 months, gross unrealized losses		0
12 months or more, estimated fair value		10,215
12 months or more, gross unrealized losses		150
Total, estimated fair value		10,215
Total, gross unrealized losses		150
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value		0
Less than 12 months, gross unrealized losses		0
12 months or more, estimated fair value		9,998
12 months or more, gross unrealized losses		67
Total, estimated fair value		9,998
Total, gross unrealized losses		67
Corporate notes [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	30,992
Less than 12 months, gross unrealized losses	25
Total, estimated fair value	30,992
Total, gross unrealized losses	$ 25