(Purchase Price and Fair Value of Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 06, 2015	Sep. 30, 2015	Dec. 31, 2014
Net Assets at Fair Value [Roll Forward]
Goodwill		$ 133,201	$ 98,562
NB&T Financial Group, Inc.
Purchase Price [Roll Forward]
Common shares outstanding of acquired company at acquisition date	3,442,329
Cash purchase price (in dollars per share)	$ 23.70
Cash in lieu of fractional shares issued		4
Number of common shares of Peoples issued for each common share of acquired company	0.9319
Total purchase price	$ 102,709
Net Assets at Fair Value [Roll Forward]
Cash and cash equivalents	124,825
Bank premises and equipment, net	10,702
Other intangible assets	10,130
Other assets	23,889
Total assets	710,526
Deposits	629,512
Borrowings	6,570
Accrued expenses and other liabilities	5,941
Total liabilities	642,023
Net assets	68,503
Goodwill	$ 34,206	$ 34,200
Cash Portion of Purchase Price | NB&T Financial Group, Inc.
Purchase Price [Roll Forward]
Cash purchase price (in dollars per share)	$ 7.75
Purchase price	$ 26,678
Stock Portion of Purchase Price | NB&T Financial Group, Inc.
Purchase Price [Roll Forward]
Purchase price	76,027
Debt Securities | NB&T Financial Group, Inc.
Net Assets at Fair Value [Roll Forward]
Debt securities and loans	156,392
Loans | NB&T Financial Group, Inc.
Net Assets at Fair Value [Roll Forward]
Debt securities and loans	$ 384,588