Investment Securities (Continuous Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	$ 12,795	$ 233,973
Less than 12 months, gross unrealized losses	30	3,567
12 months or more, estimated fair value	127,888	132,784
12 months or more, gross unrealized losses	804	5,734
Total, estimated fair value	140,683	366,757
Total, gross unrealized losses	834	9,301
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	0	110,312
Less than 12 months, gross unrealized losses	0	1,953
12 months or more, estimated fair value	12,739	34,872
12 months or more, gross unrealized losses	13	829
Total, estimated fair value	12,739	145,184
Total, gross unrealized losses	13	2,782
Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	12,795	344,285
Less than 12 months, gross unrealized losses	30	5,520
12 months or more, estimated fair value	140,627	167,656
12 months or more, gross unrealized losses	817	6,563
Total, estimated fair value	153,422	511,941
Total, gross unrealized losses	847	12,083
Residential mortgage-backed securities - GSE [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	0	137,998
Less than 12 months, gross unrealized losses	0	2,560
12 months or more, estimated fair value	119,845	132,148
12 months or more, gross unrealized losses	671	5,729
Total, estimated fair value	119,845	270,146
Total, gross unrealized losses	671	8,289
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	0	83,014
Less than 12 months, gross unrealized losses	0	1,481
12 months or more, estimated fair value	12,739	34,872
12 months or more, gross unrealized losses	13	829
Total, estimated fair value	12,739	117,886
Total, gross unrealized losses	13	2,310
Residential mortgage-backed securities - Private [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	2,791	26,265
Less than 12 months, gross unrealized losses	28	231
12 months or more, estimated fair value	621	636
12 months or more, gross unrealized losses	5	5
Total, estimated fair value	3,412	26,901
Total, gross unrealized losses	33	236
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value		17,414
Less than 12 months, gross unrealized losses		298
12 months or more, estimated fair value		0
12 months or more, gross unrealized losses		0
Total, estimated fair value		17,414
Total, gross unrealized losses		298
Commercial mortgage-backed securities - GSE [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value		21,612
Less than 12 months, gross unrealized losses		368
12 months or more, estimated fair value		0
12 months or more, gross unrealized losses		0
Total, estimated fair value		21,612
Total, gross unrealized losses		368
Commercial mortgage-backed securities - Private [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	0	17,575
Less than 12 months, gross unrealized losses	0	294
12 months or more, estimated fair value	7,422	0
12 months or more, gross unrealized losses	128	0
Total, estimated fair value	7,422	17,575
Total, gross unrealized losses	128	294
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value		9,884
Less than 12 months, gross unrealized losses		174
12 months or more, estimated fair value		0
12 months or more, gross unrealized losses		0
Total, estimated fair value		9,884
Total, gross unrealized losses		174
Corporate notes [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, estimated fair value	10,004	30,523
Less than 12 months, gross unrealized losses	2	114
12 months or more, estimated fair value	0	0
12 months or more, gross unrealized losses	0	0
Total, estimated fair value	10,004	30,523
Total, gross unrealized losses	$ 2	$ 114