Investment Securities (Held-to-maturity Securities with Unrealized Loss) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 securities	Dec. 31, 2012 securities
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	$ 25,644	$ 2,398
Less than 12 months, unrealized loss	741	41
Less than 12 months, no. of securities	6	2
12 months or more, fair value	0	0
12 months or more, unrealized loss	0	0
12 months or more, no. of securities	0	0
Total fair value	25,644	2,398
Total unrealized loss	741	41
Residential mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	18,903	0
Less than 12 months, unrealized loss	680	0
Less than 12 months, no. of securities	5	0
12 months or more, fair value	0	0
12 months or more, unrealized loss	0	0
12 months or more, no. of securities	0	0
Total fair value	18,903	0
Total unrealized loss	680	0
Commercial mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	6,741	2,398
Less than 12 months, unrealized loss	61	41
Less than 12 months, no. of securities	1	2
12 months or more, fair value	0	0
12 months or more, unrealized loss	0	0
12 months or more, no. of securities	0	0
Total fair value	6,741	2,398
Total unrealized loss	$ 61	$ 41