Fair Value Measurements (Narrative) (Details) (USD $)	15 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Noncovered [Member]	Dec. 31, 2013 Noncovered [Member]	Dec. 31, 2013 Covered [Member]
Finite-Lived Intangible Assets [Line Items]
Private equity investment Southwest's proportionate share of the net asset value	$ 2,500,000	$ 2,400,000
Noncovered impaired loans carrying amount			37,000,000	45,500,000
Noncovered impaired loans measured at fair value			30,100,000	32,300,000
Noncovered impaired loans life to date impairment			6,900,000	27,300,000
Provision for loan losses			5,300,000	100,000
Impairment charge of other real estate assets				1,500,000	700,000
Impairment charges of mortgage loan servicing rights	$ 0