Summary of Significant Accounting Policies - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income loss available to common stockholders
Net income attributable to Penn National Gaming, Inc.									$ 93,519	$ 473,463	$ 109,310
Net income applicable to preferred stock									0	0	8,662
Net income applicable to common stock									$ 93,519	$ 473,463	$ 100,648
Determination of shares:
Weighted average basic shares outstanding (in shares)									97,105,000	90,854,000	82,929,000
Diluted weighted-average common shares outstanding before participating security (in shares)									100,338,000	93,378,000	84,270,000
Assumed conversion of preferred stock (in shares)									0	0	7,137,000
Diluted weighted-average common shares outstanding (in shares)									100,338,000	93,378,000	91,407,000
Anti-dilutive securities, stock options (in shares)									656,588	51,803	3,036,819
Calculation of basic EPS:
Net income applicable to common stock									$ 93,519	$ 473,463	$ 100,648
Weighted average basic shares outstanding (in shares)									97,105,000	90,854,000	82,929,000
Basic EPS (in dollars per share)	$ (0.37)	$ 0.39	$ 0.59	$ 0.50	$ (3.72)	$ 8.68	$ 0.19	$ 0.06	$ 0.96	$ 5.21	$ 1.21
Calculation of diluted EPS using two class method:
Net income applicable to common stock									$ 93,519	$ 473,463	$ 100,648
Diluted weighted-average common shares outstanding before participating security (in shares)									100,338,000	93,378,000	84,270,000
Diluted EPS (in dollars per share)	$ (0.37)	$ 0.38	$ 0.57	$ 0.48	$ (3.72)	$ 8.43	$ 0.18	$ 0.06	$ 0.93	$ 5.07	$ 1.19
Stock options
Determination of shares:
Assumed conversion of dilutive employee stock-based awards and restricted stock (in shares)									3,018,000	2,431,000	1,299,000
Restricted stock
Determination of shares:
Assumed conversion of dilutive employee stock-based awards and restricted stock (in shares)									215,000	93,000	42,000
Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Conversion of Series C preferred stock (in shares)											8,624,000
Series C Preferred stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Conversion of Series C preferred stock (in shares)											8,624
Preferred stock, shares outstanding	0				0				0	0