Fair Value Measurements (Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Fair Value Inputs Assets Quantitative Information [Line Items]
Asset transfers	$ 0	$ 0
Assets, fair value	4,333,030,000		3,658,990,000
Other debt securities [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Assets, fair value	8,268,000		7,761,000
Private Label Residential Mortgage-Backed Securities and CMOs [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Assets, fair value	424,493,000		310,118,000
Private label residential mortgage-backed securities and CMO's - Investment grade [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Current subordination level	15.50%
Private label residential mortgage-backed securities and CMO's - Non-investment grade [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Current subordination level	10.70%
Private label residential mortgage-backed securities and CMO's - Option-arm [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Current subordination level	3.70%
Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Assets, fair value	179,006,000		204,044,000
Fair Value, Inputs, Level 3 [Member] | Other debt securities [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Assets, fair value	4,924,000		4,601,000
Fair Value, Inputs, Level 3 [Member] | Private Label Residential Mortgage-Backed Securities and CMOs [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Assets, fair value	174,026,000		199,408,000
Fair Value, Inputs, Level 3 [Member] | Private label residential mortgage-backed securities and CMO's - Investment grade [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Assets, fair value	93,136,000
Fair Value, Inputs, Level 3 [Member] | Private label residential mortgage-backed securities and CMO's - Non-investment grade [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Assets, fair value	45,901,000
Fair Value, Inputs, Level 3 [Member] | Private label residential mortgage-backed securities and CMO's - Option-arm [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Assets, fair value	34,989,000
Fair value of Level 3 securities with zero subordination	$ 28,000,000