Loans Receivable and Allowance for Loan Losses - Accretable Yield Movement Schedule on Acquired Credit Impaired Loans in Center Merger (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	$ 32,583	$ 23,410	$ 47,398	$ 18,651
Additions due to acquisitions during the period	0	0	0	4,945
Accretion	(4,197)	(3,586)	(9,064)	(7,032)
Changes in expected cash flows	(102)	17,266	(10,050)	20,526
Balance at end of period	$ 28,284	$ 37,090	$ 28,284	$ 37,090