Business Combinations (Pro Forma Results of Operations) (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended			6 Months Ended				12 Months Ended	3 Months Ended			6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended				6 Months Ended				3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013		Dec. 31, 2013	Jun. 30, 2014 Sterling Financial Corporation [Member]	Jun. 30, 2014 Sterling Financial Corporation [Member] Acquisition-related Costs [Member]	Jun. 30, 2013 Sterling Financial Corporation [Member] Acquisition-related Costs [Member]	Jun. 30, 2014 Sterling Financial Corporation [Member] Acquisition-related Costs [Member]	Jun. 30, 2013 Sterling Financial Corporation [Member] Acquisition-related Costs [Member]	Jun. 30, 2014 Financial Pacific Holding Corp [Member]	Jun. 30, 2014 Financial Pacific Holding Corp [Member]	Jun. 30, 2013 Financial Pacific Holding Corp [Member] Acquisition-related Costs [Member]	Jun. 30, 2013 Financial Pacific Holding Corp [Member] Acquisition-related Costs [Member]	Jun. 30, 2014 Pro Forma [Member] Sterling Financial Corporation [Member]		Jun. 30, 2013 Pro Forma [Member] Sterling Financial Corporation [Member]		Jun. 30, 2014 Pro Forma [Member] Sterling Financial Corporation [Member]		Jun. 30, 2013 Pro Forma [Member] Sterling Financial Corporation [Member]		Jun. 30, 2013 Pro Forma [Member] Financial Pacific Holding Corp [Member]	Jun. 30, 2013 Pro Forma [Member] Financial Pacific Holding Corp [Member]
Business Acquisition, Pro Forma Information [Abstract]
Net interest income									$ 101,254,000
Provision for loan losses									7,735,000
Non-interest income									22,302,000
Non-interest expense, excluding merger expense									65,132,000
Merger expense									57,531,000
Income tax benefit									1,101,000
Net loss									(5,741,000)
Net interest income	212,259,000	93,893,000		320,097,000		188,082,000												234,503,000	[1],[2]	214,107,000	[1],[2]	458,792,000	[1],[2]	427,140,000	[1],[2]	105,297,000	210,809,000
Provision for non-covered loan and lease losses	15,399,000	2,993,000		20,799,000		9,981,000												15,399,000		2,993,000		20,799,000		9,981,000		3,688,000	13,253,000
RECAPTURE OF PROVISION FOR COVERED LOAN LOSSES	(703,000)	(3,072,000)		(132,000)		(2,840,000)												(703,000)		(3,072,000)		(132,000)		(2,840,000)		(3,072,000)	(2,840,000)
Non-interest income	44,529,000	34,497,000		67,536,000		68,512,000												48,785,000	[3],[4],[5]	71,567,000	[3],[4],[5]	94,107,000	[3],[4],[5]	138,718,000	[3],[4],[5]	35,019,000	69,824,000
Non-interest expense	214,131,000	87,931,000		310,649,000		173,693,000								3,700,000	7,600,000			175,480,000	[6],[7]	241,906,000	[6],[7]	349,705,000	[6],[7]	419,915,000	[6],[7]	92,403,000	181,794,000
Income before income taxes	27,961,000	40,538,000		56,317,000		75,760,000												93,112,000		43,847,000		182,527,000		138,802,000		47,297,000	88,426,000
Provision for income taxes	10,740,000	14,285,000		20,332,000		26,146,000												36,637,000		12,822,000		68,905,000		45,039,000		16,910,000	31,094,000
Net income	17,221,000	26,253,000		35,985,000		49,614,000		98,361,000						3,900,000	8,200,000			56,475,000		31,025,000		113,622,000		93,763,000		30,387,000	57,332,000
Dividends and undistributed earnings allocated to participating securities	83,000	197,000	[8]	196,000	[8]	380,000	[8]											83,000		197,000		196,000		380,000		228,000	439,000
Net earnings available to common shareholders	17,138,000	26,056,000		35,789,000		49,234,000				2,800,000	20,400,000	23,400,000	42,500,000			(820,000)	(1,500,000)	56,392,000		30,828,000		113,426,000		93,383,000		30,159,000	56,893,000
Earnings per share:
Basic (in usd per share)	$ 0.09	$ 0.23		$ 0.23		$ 0.44												$ 0.26		$ 0.14		$ 0.52		$ 0.43		$ 0.27	$ 0.51
Diluted (in usd per share)	$ 0.09	$ 0.23		$ 0.23		$ 0.44												$ 0.26		$ 0.14		$ 0.52		$ 0.43		$ 0.27	$ 0.51
Average shares outstanding:
Basic (in shares)	196,312	111,954		154,473		111,946												217		216		217		216		111,954	111,946
Diluted (in shares)	197,638	112,145		155,276		112,133												221		218		220		218		112,145	112,133
Footnote Information [Abstract]
Accretion of loan discounts																		5,100,000		33,600,000		31,900,000		69,800,000
Amortization of deposit and borrowings premiums																		1,000,000		5,600,000		5,900,000		11,400,000
Loss on service charges due to exceeding $10 billion asset threshold																		288,000		1,400,000		1,700,000		2,900,000
Change in junior subordinated debentures carried at fair value				(2,631,000)		(1,078,000)												(190,000)		(966,000)		(837,000)		(1,900,000)
Reversal of provision for loss on divestiture																						7,000,000
Amortization of core deposit intangibles																		347,000		2,000,000		2,100,000		4,100,000
Adjustment to merger related expenses																		$ 70,700,000				$ 79,400,000

[1] Includes $5.1 million and $33.6 million of incremental loan discount accretion for the three months ended June 30, 2014 and 2013, respectively and $31.9 million and $69.8 million for the six months ended June 30, 2014 and 2013, respectively.

[2] Includes a reduction of interest expense of $1.0 million and $5.6 million related to deposit and borrowing premiums amortization for the three months ended June 30, 2014 and 2013, respectively and $5.9 million and $11.4 million for the six months ended June 30, 2014 and 2013, respectively.

[3] Includes a loss on junior subordinated debentures carried at fair value of $190,000 and $966,000 for the three months ended June 30, 2014 and 2013, respectively and $837,000 and $1.9 million for six months ended June 30, 2014 and 2013, respectively.

[4] Includes a reduction of service charges on deposit of $288,000 and $1.4 million as a result of passing the $10 billion asset threshold for the three months ended June 30, 2014 and 2013, respectively and $1.7 million and $2.9 million for the six months ended June 30, 2014 and 2013, respectively.

[5] The six months ended June 30, 2014 includes the reversal of the $7.0 million loss on the sale of the six stores.

[6] Includes $347,000 and $2.0 million of incremental core deposit intangible amortization for the three months ended June 30, 2014 and 2013, respectively and $2.1 million and $4.1 million for the six months ended June 30, 2014 and 2013, respectively.

[7] The three and six months ended June 30, 2014 were adjusted to exclude $70.7 million and $79.4 million of merger expenses, respectively, the three and six months ended June 2013 were adjusted to include these charges.

[8] Represents dividends paid and undistributed earnings allocated to nonvested restricted stock awards.