Investment Securities (Continuous Unrealized Loss Position) (Details) $ in Thousands	Dec. 31, 2015 USD ($) securities	Dec. 31, 2014 USD ($) securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Estimated Fair Value	$ 233,973	$ 1,154
Less than 12 Months, Gross Unrealized Losses	3,567	4
12 Months or More, Estimated Fair Value	132,784	277,630
12 Months or More, Gross Unrealized Losses	5,734	6,162
Total, Estimated Fair Value	366,757	278,784
Total, Gross Unrealized Losses	9,301	6,166
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Estimated Fair Value	110,312	0
Less than 12 Months, Gross Unrealized Losses	1,953	0
12 Months or More, Estimated Fair Value	34,872	122,876
12 Months or More, Gross Unrealized Losses	829	1,702
Total, Estimated Fair Value	145,184	122,876
Total, Gross Unrealized Losses	2,782	1,702
Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Estimated Fair Value	344,285	1,154
Less than 12 Months, Gross Unrealized Losses	5,520	4
12 Months or More, Estimated Fair Value	167,656	400,506
12 Months or More, Gross Unrealized Losses	6,563	7,864
Total, Estimated Fair Value	511,941	401,660
Total, Gross Unrealized Losses	$ 12,083	$ 7,868
Number of securities with losses for more than twelve months | securities	18	42
Residential mortgage-backed securities - GSE [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Estimated Fair Value	$ 137,998	$ 0
Less than 12 Months, Gross Unrealized Losses	2,560	0
12 Months or More, Estimated Fair Value	132,148	245,457
12 Months or More, Gross Unrealized Losses	5,729	5,593
Total, Estimated Fair Value	270,146	245,457
Total, Gross Unrealized Losses	8,289	5,593
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Estimated Fair Value	83,014	0
Less than 12 Months, Gross Unrealized Losses	1,481	0
12 Months or More, Estimated Fair Value	34,872	112,878
12 Months or More, Gross Unrealized Losses	829	1,635
Total, Estimated Fair Value	117,886	112,878
Total, Gross Unrealized Losses	2,310	1,635
Residential mortgage-backed securities - Private [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Estimated Fair Value	26,265	1,154
Less than 12 Months, Gross Unrealized Losses	231	4
12 Months or More, Estimated Fair Value	636	0
12 Months or More, Gross Unrealized Losses	5	0
Total, Estimated Fair Value	26,901	1,154
Total, Gross Unrealized Losses	236	4
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	0
Less than 12 Months, Gross Unrealized Losses	368	0
12 Months or More, Estimated Fair Value	0	21,958
12 Months or More, Gross Unrealized Losses	0	419
Total, Estimated Fair Value	21,612	21,958
Total, Gross Unrealized Losses	368	419
Corporate Notes [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Estimated Fair Value	30,523
Less than 12 Months, Gross Unrealized Losses	114
12 Months or More, Estimated Fair Value	0
12 Months or More, Gross Unrealized Losses	0
Total, Estimated Fair Value	30,523
Total, Gross Unrealized Losses	114
Commercial mortgage-backed securities - Private [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Estimated Fair Value	17,575	0
Less than 12 Months, Gross Unrealized Losses	294	0
12 Months or More, Estimated Fair Value	0	10,215
12 Months or More, Gross Unrealized Losses	0	150
Total, Estimated Fair Value	17,575	10,215
Total, Gross Unrealized Losses	294	150
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Estimated Fair Value	9,884	0
Less than 12 Months, Gross Unrealized Losses	174	0
12 Months or More, Estimated Fair Value	0	9,998
12 Months or More, Gross Unrealized Losses	0	67
Total, Estimated Fair Value	9,884	9,998
Total, Gross Unrealized Losses	$ 174	$ 67