Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities
Net loss	$ (29,057)	$ (41,233)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	612	849
Change in valuation of warrant liability	0	(47)
Non-cash interest expense	1,600	1,446
Amortization of premiums on investments	208	631
Amortization of debt issuance costs	80	72
Share-based compensation expense	9,029	8,915
Unrealized foreign currency transaction losses, net	820	0
Changes in operating assets and liabilities:
Inventory	(1,350)	0
Prepaid expenses and other current assets	93	702
Trade receivables, net	(6,746)	(10,678)
Deposits and other assets	(226)	(12)
Accounts payable and accrued expenses	(3,923)	(2,452)
Other liabilities	(624)	(23)
Deferred revenue	582	243
Net cash used in operating activities	(28,902)	(41,587)
Cash flows from investing activities
Purchases of fixed assets	(225)	(265)
Purchases of marketable securities	(19,467)	(19,413)
Sale and redemption of marketable securities	44,110	41,795
Net cash provided by investing activities	24,418	22,117
Cash flows from financing activities
Proceeds from exercise of options	106	34
Proceeds from shares issued under employee stock purchase plan	557	0
Net cash provided by financing activities	663	34
Effect of exchange rate changes on cash	(394)	1,579
Net decrease in cash and cash equivalents	(4,215)	(17,857)
Cash and cash equivalents, beginning of period	58,321	58,022
Cash and cash equivalents, end of period	54,106	40,165
Supplemental disclosure of cash information
Cash paid for interest	2,250	2,263
Cash paid for income taxes	28	225
Supplemental disclosures of non-cash information related to investing and financing activities
Change in unrealized (loss) gain on marketable securities, net of tax	$ (22)	$ 658

Represents change in the unrealized gain (loss) on marketable securities in noncash investing and financing activities.

No definition available.

Name:	ptct_ChangeInUnrealizedGainLossOnMarketableSecurities
Namespace Prefix:	ptct_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method.